Plant adaptation to environmental change- significance of amino acids and their derivatives.pdf

Plant Adaptation to Environmental Change
Signiﬁcance of Amino Acids and their Derivatives

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Plant Adaptation to
Environmental Change
Signiﬁcance of Amino Acids and their Derivatives
Edited by
Naser A. Anjum
CESAM-Centre for Environmental and Marine Studies
& Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
Sarvajeet S. Gill and Ritu Gill
Centre for Biotechnology, MD University Rohtak – 124 001, Haryana, India

© CAB International 2014. All rights reserved. No part of this publication may be
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photocopying, recording or otherwise, without the prior permission of the
copyright owners.
A catalogue record for this book is available from the British Library, London, UK.
Library of Congress Cataloging-in-Publication Data
Plant adaptation to environmental change : significance of amino acids and their
derivatives / edited by Naser A. Anjum, Sarvajeet S. Gill and Ritu Gill.
p. ; cm.
Includes bibliographical references and index.
ISBN 978-1-78064-273-4 (alk. paper)
1. Crops--Effect of stress on. 2. Crops--Adaptation. 3. Crops--Physiology.
4. Amino acids. 5. Polyamines. I. Anjum, Naser A. II. Gill, Sarvajeet Singh.
III. Gill, Ritu.
QK754.P55 2013
571.2--dc23
2013021988
ISBN-13: 978 1 78064 273 4
Commissioning editor: Sreepat Jain
Editorial assistant: Alexandra Lainsbury
Production editors: Shankari Wilford and Simon Hill
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v
Contents
Contributors vii
Preface x
Acknowledgements xii
Abbreviations xiii
part i: introduction
1 Environmental Change, and Plant Amino Acids and their Derivatives –
An Introduction 1
Naser A. Anjum, Sarvajeet S. Gill, Imran Khan and Ritu Gill
part ii: amino acids and peptides, and plant stress adaptation
2 5-Aminolevulinic Acid (5-ALA) – A Multifunctional Amino Acid
as a Plant Growth Stimulator and Stress Tolerance Factor 18
Yoshikatsu Murooka and Tohru Tanaka
3 Cysteine – Jack of All Glutathione-based Plant Stress Defence Trades 35
Naser A. Anjum, Sarvajeet S. Gill and Ritu Gill
4 Amino Acids and Drought Stress in Lotus: Use of Transcriptomics
and Plastidic Glutamine Synthetase Mutants for New Insights
in Proline Metabolism 53
Pedro Díaz, Marco Betti, Margarita García-Calderón, Carmen M. Pérez-Delgado,
Santiago Signorelli, Omar Borsani, Antonio J. Márquez and Jorge Monza
5 Modulation of Proline: Implications in Plant Stress Tolerance and Development 68
P. Suprasanna, Archana N. Rai, P. HimaKumari, S. Anil Kumar and P.B. KaviKishor
6 Target Osmoprotectants for Abiotic Stress Tolerance in Crop Plants –
Glycine Betaine and Proline 97
Sarvajeet S. Gill, Ritu Gill and Naser A. Anjum

vi Contents
part iii: amines and brassinosteroids, and plant stress adaptation
7 Polyamines as Indicators and as Modulators of the Abiotic Stress in Plants 109
Pablo Ignacio Calzadilla, Ayelén Gazquez, Santiago Javier Maiale, Oscar Adolfo Ruiz
and Menéndez Ana Bernardina
8 Polyamines in Stress Protection – Applications in Agriculture 129
Rubén Alcázar and Antonio F. Tiburcio
9 Functional Role of Polyamines and Polyamine-metabolizing
Enzymes during Salinity, Drought and Cold Stresses 141
Aryadeep Roychoudhury and Kaushik Das
10 Regulatory Role of Polyamines in Growth, Development
and Abiotic Stress Tolerance in Plants 157
Mirza Hasanuzzaman, Kamrun Nahar and Masayuki Fujita
11 Polyamines – Involvement in Plant Stress Tolerance and Adaptation 194
Dessislava Todorova, Zornitsa Katerova, Iskren Sergiev and Vera Alexieva
12 Role of Polyamines in Plant–Pathogen Interactions 222
Abhijit Dey, Kamala Gupta and Bhaskar Gupta
13 Role of Polyamines in Stress Management 245
Renu Bhardwaj, Indu Sharma, Neha Handa, Dhriti Kapoor, Harpreet Kaur,
Vandana Gautam and Sukhmeen Kohli
14 Polyamines in Plant In Vitro Culture 266
Jose Luis Casas
15 Betaines and Related Osmoprotectants – Significance
in Metabolic Engineering of Plant Stress Resistance 281
Renu Bhardwaj, Indu Sharma, Resham Sharma and Poonam
16 Brassinosteroids’ Role for Amino Acids, Peptides and Amines Modulation
in Stressed Plants – A Review 300
B. Vidya Vardhini
part iv: appraisal and perspectives
17 Plant Adaptation to Environmental Change, and Significance
of Amino Acids and their Derivatives – Appraisal and Perspectives 317
Naser A. Anjum, Sarvajeet S. Gill and Ritu Gill
Index 319

Contributors
Rubén Alcázar, Department of Natural Products and Plant Biology, University of Barcelona, Faculty
of Pharmacy, Avda de Joan XXIII s/n, 08028 Barcelona, Spain
Vera Alexieva, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G.
Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria. e-mail: verea@bio21.bas.bg
Naser A. Anjum, CESAM-Centre for Environmental and Marine Studies & Department of Chemistry,
University of Aveiro, Portugal. e-mail: anjum@ua.pt; dnaanjum@gmail.com
Menéndez Ana Bernardina, IIB-INTECh (CONICET-UNSAM), Chascomús, Buenos Aires, Argen-
tina; Department of Biodiversity and Experimental Biology, Faculty of Sciences, University of Buenos
Aires (DBBE, FCEN, UBA)
Marco Betti, Department of Plant Biochemistry and Molecular Biology, Chemistry Faculty, Univer-
sity of Seville, Apartado 1203, 41071-Sevilla, Spain
Renu Bhardwaj, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
Amritsar 143005, Punjab, India. e-mail: dr.renubhardwaj@yahoo.in; renubhardwaj82@gmail.com
Omar Borsani, Biochemistry Laboratory, Department of Vegetal Biology, Agronomy Faculty, Research
group: Plant Abiotic Stress, Av. E. Garzón 780, CP 12900 Montevideo, Uruguay
Pablo Ignacio Calzadilla, IIB-INTECh (CONICET-UNSAM), Chascomús, Buenos Aires, Argentina
Jose Luis Casas, Plant Biotechnology Laboratory, Institute of Biodiversity (CIBIO), University of
Alicante, Crta. San Vicente del Raspeig s/n, E-03690 San Vicente del Raspeig, Alicante, Spain. e-mail:
jl.casas@ua.es
Kaushik Das, Post Graduate Department of Biotechnology, St. Xavier’s College (Autonomous), 30,
Mother Teresa Sarani, Kolkata – 700016, West Bengal, India
Abhijit Dey, Department of Botany, Presidency University, 86/1 College Street, Kolkata 700073,
India
Pedro Díaz, BiochemistryLaboratory,DepartmentofVegetalBiology,AgronomyFaculty,Researchgroup:
Plant Abiotic Stress, Av. E. Garzón 780, CP 12900 Montevideo, Uruguay
Masayuki Fujita, Laboratory of Plant Stress Responses, Department of Applied Biological Science,
Kagawa University, 2393 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan. e-mail: fujita@ag
.kaga-u.ac.jp
Margarita García-Calderón, Department of Plant Biochemistry and Molecular Biology, Chemistry
Faculty, University of Seville, Apartado 1203, 41071-Sevilla, Spain
Vandana Gautam,DepartmentofBotanicalandEnvironmentalSciences,GuruNanakDevUniversity,
Amritsar 143005, Punjab, India
vii

viii Contributors
Ayelén Gazquez, IIB-INTECh (CONICET-UNSAM), Chascomús, Buenos Aires, Argentina
Ritu Gill, Centre for Biotechnology, MD University, Rohtak, Haryana, India
Sarvajeet S. Gill, Centre for Biotechnology, MD University, Rohtak, Haryana, India. e-mail: ssgill14@
gmail.com
Bhaskar Gupta, Molecular Biology Laboratory, Department of Biotechnology, Presidency University,
86/1 College Street, Kolkata 700073, India.e-mail: bhaskarzoology@gmail.com
Kamala Gupta, Plant Molecular Biology Laboratory, Department of Botany, Bethune College, 181
Bidhan Sarani, Kolkata 700006, India
Neha Handa, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
Mirza Hasanuzzaman, Laboratory of Plant Stress Responses, Department of Applied Biological
Science, Kagawa University, 2393 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan; Department
of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh
Dhriti Kapoor, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
Zornitsa Katerova, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad.
G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
Harpreet Kaur, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
P.B. KaviKishor, Department of Genetics, Osmania University, Hyderabad 500 007, India
Sukhmeen Kohli, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
Imran Khan, Department of Chemistry, CICECO, University of Aveiro, Campus Universitário de
Santiago, 3810-193 Aveiro, Portugal
S. Anil Kumar, Department of Genetics, Osmania University, Hyderabad 500 007, India
P. Hima Kumari, Department of Genetics, Osmania University, Hyderabad 500 007, India
Santiago Javier Maiale, IIB-INTECh (CONICET-UNSAM), Chascomús, Buenos Aires, Argentina
Antonio J. Márquez, Department of Plant Biochemistry and Molecular Biology, Chemistry Faculty,
University of Seville, Apartado 1203, 41071-Sevilla, Spain. e-mail: cabeza@us.es
Jorge Monza, Biochemistry Laboratory, Department of Vegetal Biology, Agronomy Faculty, Research
group: Plant Abiotic Stress, Av. E. Garzón 780, CP 12900 Montevideo, Uruguay
Yoshikatsu Murooka, Emeritus Professor of Osaka University, Takaya, Higashi-Hiroshima
739-2125, Japan. email: murooka@bio.eng.osaka-u.ac.jp
Kamrun Nahar, Laboratory of Plant Stress Responses, Department of Applied Biological Science,
Kagawa University, 2393 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan; Department of
Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka-1207,
Bangladesh
Carmen M. Pérez-Delgado, Department of Plant Biochemistry and Molecular Biology, Chemistry
Faculty, University of Seville, Apartado 1203, 41071-Sevilla, Spain
Poonam, Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amrit-
sar 143005, Punjab, India
Archana N. Rai, Nuclear Agriculture Biotechnology, Bhabha Atomic Research Center, Trombay,
Mumbai 400 085, India
Aryadeep Roychoudhury, Post Graduate Department of Biotechnology, St. Xavier’s College (Autono-
mous), 30, Mother Teresa Sarani, Kolkata – 700016, West Bengal, India. e-mail: aryadeep.rc@gmail.
com
Oscar Adolfo Ruiz, IIB-INTECh (CONICET-UNSAM), Chascomús, Buenos Aires, Argentina. e-mail:
ruiz@intech.gov.ar; oruiz@iib.unsam.edu.ar
Iskren Sergiev, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G.
Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
Indu Sharma, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,

Contributors ix
Resham Sharma, Department of Botanical and Environmental Sciences, Guru Nanak Dev University,
Santiago Signorelli, Biochemistry Laboratory, Department of Vegetal Biology, Agronomy Faculty,
Research group: Plant Abiotic Stress, Av. E. Garzón 780, CP 12900 Montevideo, Uruguay
P. Suprasanna, Nuclear Agriculture Biotechnology, Bhabha Atomic Research Center, Trombay, Mum-
bai 400 085, India. e-mail: penna888@yahoo.com
Tohru Tanaka, SBI Pharmaceuticals Co., Ltd., 1-6-1 Roppongi, Minato-ku, Tokyo 106-6017, Japan
Antonio F. Tiburcio, Department of Natural Products and Plant Biology, University of Barcelona,
Faculty of Pharmacy, Avda de Joan XXIII s/n, 08028 Barcelona, Spain. e-mail: afernandez@ub.edu
Dessislava Todorova, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences,
Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
B. Vidya Vardhini, Department of Botany, Telangana University, Nizamabad-503175, Andhra
Pradesh, India. e-mail: drvidyavardhini@rediffmail.com

x
Preface
Plants are fundamental to all life on Earth. They provide us with oxygen, food, fuel, fibre, medicines
and even shelter, either directly or indirectly. However, plant-based food production has always been
linked to environmental changes. To this end, both naturally and human activities-inﬂuenced changes
in the physical and biogeochemical environments contribute to global environmental changes which
cumulatively create sub-optimal conditions for plant growth. Being sessile in nature, plants, in a vari-
ably changing environment, have to cope with a plethora of sub-optimal (adverse) growth conditions
where the majority of these conditions can delay growth and development and most importantly pre-
vent them reaching their full productivity genetic potential. Nevertheless, in the complex field envi-
ronment with its heterogenic conditions, global environmental changes-mediated potential anomalies
in plants are further aggravated with various abiotic stress combinations. However, plants develop a
battery of highly sophisticated and efficient strategies to acclimate, grow and produce under gradual
change in their environment. Understanding of the global environmental change-led impacts on
plants and also the exploration of sustainable ways to counteract these impacts have become thrust
areas of utmost significance.
Through authoritative contributions, the present volume entitled Plant Adaptation to Environmen-
tal Change: Significance of Amino Acids and their Derivatives overviews varied amino acids and their
derivatives’ significance for plant stress adaptation/tolerance, discusses significant biotechnological
strategies for the manipulation of amino acids and their major derivatives (hence to improve biotic/
abiotic stress tolerance in crop plants), provides state-of-the-art knowledge of recent developments in
the understanding of amino acids and their derivatives emphasizing mainly on the cross-talks on
amino acids, peptides and amines, and fills the gap in the knowledge gained on the subject obtained
through extensive research in the last one and half decades.
In particular, the role of important amino acids, peptides and amines as potential selection crite-
ria for improving plant tolerance to adverse growth conditions has been critically discussed at length
in different chapters contributed by experts from over the globe working in the field of crop improve-
ment, genetic engineering and abiotic stress tolerance. Though occasional overlaps of information
between chapters could not be avoided, they reflect the central and multiple aspects of major amino
acids, peptides and amines-based strategies for enhancing tolerance to environmental change in the
light of the advances in molecular biology.
Chapter 1 introduces major factors responsible for environmental change and its implication for
plant growth and development, and amino acids and their important derivatives in context mainly
with their significance for plant adaptation and/or tolerance to varied environmental stress factors.

Preface xi
Focusing on 5-aminolevulinic acid (5-ALA) Chapter 2 deals with the biosynthetic pathway and chemi-
cal synthesis of 5-ALA, the biosynthetic pathway of tetrapyrrole compounds from 5-ALA, industrial
strains development for 5-ALA over-production and 5-ALA important biological activity significance
in different stressed plants. Chapter 3 summarizes available data on the structure, occurrence, biosyn-
thesis, regulation and significance of cysteine, peptides (glutathione, phytochelatins) and cysteine-
rich, gene-encoded low-molecular weight proteins – metallothioneines in plant metabolism and stress
defense as well. Considering the significance of legumes for both humans and animals as a source of
protein-rich food Chapter 4 discusses transcriptomics and plastidic glutamine synthetase mutants for
new insights in proline metabolism in drought exposed Lotus japonicus. In Chapter 5, information
about physiological functions and regulations of proline in plant systems is summarized and diverse
roles of proline including the signalling events involved in proline synthesis are presented. Chapter 6
reviews the knowledge that has been gathered over the last couple of decades with respect to glycine
betaine and proline – extensively explored as target osmoprotectants for enhancing abiotic stress tol-
erance in crop plants.
The central focus of Chapters 7–11 is polyamines. In particular, Chapter 7 critically discusses poly-
amines as indicators and modulators in the abiotic stress in plants. By exploring the natural variation
for polyamine levels, and how these interact with the environment, Chapter 8 looks for developing
tools that will facilitate the manipulation of polyamine levels that can lead to practical applications in
agriculture. Chapter 9 emphasizes the mechanism of polyamine metabolism and their multifunctional
role in plants under major environmental stresses like salinity, drought and cold. In addition, in this
chapter, the regulation of expression of genes, encoding polyamine-metabolizing enzymes under such
stress conditions, their promoter structures and overexpression of such genes through transgenic
approaches for enhanced tolerance is also highlighted. Chapter 10 summarizes some recent data con-
cerning changes in polyamine metabolism (biosynthesis, catabolism and regulation) in higher plants
subjected to a wide array of environmental stress conditions, and describes and discusses some new
advances concerning the different proposed mechanisms of polyamine actions implicated in plants’
responses to abiotic stress. Furthermore, this chapter also discusses progress made in genetic engi-
neering in polyamine-induced stress tolerance in plants. Polyamines involvement in plant tolerance
and adaptation to stress is discussed in Chapter 11. The role of polyamines in the biotic stress of plants
as a result of plant–pathogen interaction with a note on current research tendencies and future per-
spectives is critically discussed in Chapter 12; whereas, Chapter 13 highlights the role of polyamines in
the management of important stresses. Chapter 14 deals with polyamines significance in plant in vitro
culture. Betaines and related osmoprotectants’ significance in metabolic engineering of plant stress
resistance is highlighted in Chapter 15; whereas, Chapter 16 throws lights on brassinosteroids’ role for
amino acids, peptides and amines modulation in stressed plants. Chapter 17 presents a critical
appraisal of the manuscripts covered in the current book and also highlights important aspects so far
less explored in the current context.
The outcome of the present treatise will be a resourceful guide suited for scholars and researchers
exploring sustainable strategies for crop improvement and abiotic stress tolerance.
Naser A. Anjum
Sarvajeet S. Gill
Ritu Gill

xii
Acknowledgements
We are thankful to the competent scientists for their sincere efforts, invaluable contributions and full
faith and cooperation that eventually made the present volume possible.
We extend our appreciation to Dr. Sreepat Jain, CABI Commissioning Editor for South Asia and his
team at CABI, United Kingdom for their exceptional kind support, which made our efforts successful.
We gratefully acknowledge the Foundation for Science & Technology (FCT), Portugal, the Aveiro
University Research Institute/Centre for Environmental and Marine Studies (CESAM), University
Grants Commission (UGC) and Council for Scientific and Industrial Research, Govt. of India,
New Delhi, India for financial supports to our research.
Last but not least, we thank all the well-wishers, teachers, seniors, research students, colleagues
and our families. Without their unending moral support, motivation, endurance and encouragements,
the gruelling task would have never been accomplished. Special thanks go to Zoya, Simar Gill and
Naznee who supported us during the course of this book project.
Naser A. Anjum
Sarvajeet S. Gill
Ritu Gill

Abbreviation Name or term in full
AAME adipic acid monoethyl ester
ABA abscisic acid
ADC arginine decarboxylase
AG aminoguanidine
AIH agmatine iminohydrolase
AMF arbuscular mycorrhizal fungus
AOs amine oxidases
arg arginine
AS asparagine synthetase
asn asparagine
BA benzyladenine
CEVd citrus exocortis viroid
CHA cyclohexylamine
CMV cucumber mosaic virus
CMV-Y CMV-yellow
CP clover phyllody
CPA N-carbamoylputrescine
amidohydrolase
CuAO copper binding diamine
oxidases
DAO diamine oxidases
DAP diaminopropane
DCHA dicyclohexylamine
DFMA α-difluoromethylarginine
DFMO α-dl-difluoromethylornithine
DFMO α-difluoromethylornithine
DW dry weight
Epi epinastic
ER endoplasmic reticulum
Fd-GOGAT ferredoxin-dependent
glutamate synthase
xiii
Abbreviations
FDR false discovery rate
GA gibberellic acid
GABA gamma aminobutyric acid
GC-MS gas chromatography-mass
spectroscopy
GDC glutamate decarboxylase
GDC glycine decarboxylase
GDH glutamate dehydrogenase
gln glutamine
GLRaV grapevine leafroll associated
viruses
glu glutamate
GO glycolate oxidase
GS glutamine synthetase
GSH glutathione (reduced)
GS1 cytosolic glutamine synthetase
GS2 plastidic glutamine synthetase
GSSG glutathione (oxidized)
HCAs hydroxycinnamic acid amides
HPR hydroxypyruvate reductase
hprol hydroxyproline
HR hypersensitive response
IAA indole-3-acetic acid
IBA indole-3-butyric acid
JA jasmonic acid
LDC lysine decarboxylase
MGBG methylglyoxal bis-
(guanylhydrazone)
MIPKs mitogen-activated protein
kinases
MJ methyl jasmonate

xiv Abbreviations
mROS mitochondrial reactive
oxygen species
MTs metallothioneins
NAA naphthaleneacetic acid
NO nitric oxide
NR nitrate reductase
OAT ornithine-delta-
aminotransferase
ODC ornithine decarboxylase
orn ornithine
P5C pyrroline-5-carboxylate
P5CDH pyrroline-5-carboxylate
dehydrogenase
P5CR pyrroline-5-carboxylate
reductase
P5CS pyrroline-5-carboxylate
synthetase
PA polyamine
PAL phenylalanine ammonia lyase
PAO polyamine oxidases
PCs phytochelatins
PCD programmed cell death
PDH proline dehydrogenase
pglu pyroglutamate
PR pathogenesis-related
pro proline
Put putrescine
ROS reactive oxygen species
RWC relative water content
SAM S-adenosylmethionine
SAMDC SAM decarboxylase
Spd spermidine
Spm spermine
TMV tobacco mosaic virus
UPR unfolded protein responses
WIPK wound-induced protein kinase

© CAB International 2014. Plant Adaptation to Environmental Change
(eds N.A. Anjum, S.S. Gill and R. Gill) 1
1 Environmental Change,
and Plant Amino Acids and their
Derivatives – An Introduction
Naser A. Anjum1,*, Sarvajeet S. Gill2, Imran Khan3 and Ritu Gill2
1CESAM-Centre for Environmental and Marine Studies & Department of Chemistry,
University of Aveiro, Portugal; 2Centre for Biotechnology, MD University, Rohtak,
Haryana, India; 3Department of Chemistry, CICECO, University of Aveiro,
Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
1.1 Background
Being sessile in nature, plants, in a variably
changing environment, have to cope with a pleth-
ora of adverse growth conditions (hereafter called
stress) where the majority of these conditions can
delay growth and development and most impor-
tantly prevent them reaching their full genetic
potential in terms of productivity. Therefore,
identifying the major factors responsible for
environmental changes and understanding their
cumulative potential effects on plant growth
would be promising in sustainably protecting the
agricultural ecosystem, and hence extract enough
food for the burgeoning global population. The
interactions between plants and environmental
stresses reflect a complex system where plant
stressresponsesoccuratalllevelsoforganization.
At the cellular level, though a variety of reactive
oxygen species (ROS), including hydrogen perox-
ide (H2O2), superoxide (O2
–) and hydroxyl radical
(OH-), are by-products of the normal aerobic
plant cell metabolism, varied adverse growth con-
ditions lead to significantly elevated generation
of ROS and its reaction products (Apel and Hirt,
2004; Gill and Tuteja, 2010b). Subsequently,
an imbalance between the pro-oxidants (ROS
and its reaction products) generation and their
antioxidants-mediated metabolism/scavenging
occurs leading to a physiological condition called
oxidative stress. Unmetabolized ROS and its
reaction products are highly toxic due to their
capacity to induce oxidative damage to vital cel-
lular organelles, lipids, proteins, nucleic acids
and pigments leading ultimately to cellular
metabolism arrest.
Plants respond to the continuous environ-
mental fluctuations with appropriate physio-
logical, developmental and biochemical changes
to cope with and/or acclimatize/adapt to these
stress conditions. Plants exposed to stress
factors often synthesize a set of diverse metab-
olites that accumulate to concentrations in the
millimolar range, particularly specific amino
acids (such as asparagine, histidine, proline and
serine), peptides (such as glutathione and
phytochelatins, PCs), and the amines (such
as spermine, spermidine, putrescine, nicoti-
anamine and mugineic acids). A credible num-
ber of studies have shown the significant
* Corresponding author, e-mail: anjum@ua.pt

2 N.A. Anjum et al.
changes in the contents of the majority of
amino acids, peptides and amines, thus indicat-
ing their functional significance in the context
of stress tolerance and/or adaptations. Multiple
highly regulated and interwoven metabolic net-
works occur in plant cells where these networks
largely play central regulatory roles in plant
growth and development. Because the amino
acids are vital for the synthesis of proteins and
also serve as precursors for a large array of
metabolites with multiple functions in plant
growth and response to various stresses, the
amino acids synthesis-related metabolic net-
works have gained considerable interest (Less
and Galili, 2008).
This chapter introduces: (a) the major factors
responsible for environmental change and its
implication for plant growth and development,
and (b) amino acids and their important deriva-
tives in context mainly with their significance for
plant adaptation and/or tolerance to varied envi-
ronmental stress factors.
1.2 Environmental Change
Agricultural food production has always been
linked to environmental conditions; however,
growing demands for food in turn affect the
global environment in many ways. According to
recent estimates, global food security has been
projected to face a severe threat from global envi-
ronmental change, which includes naturally or
human activities-inﬂuenced changes in the phys-
ical and biogeochemical environments (Steffen
et al., 2003; Carpenter et al., 2009; Ericksen et al.,
2009; Liverman and Kapadia, 2010). Moreover,
different elements of environmental change are
interlinked through a complex set of physical,
chemical and biological processes; where natural
or human activities-led changes in one compo-
nent can ramify for other components as well
(IPEC, 2003).
Changes in atmospheric CO2 concentration,
increase in ambient temperatures and regional
changes in annual precipitation are expected to
significantly influence future agricultural pro-
duction (Mittler and Blumwald, 2010). During
the past two centuries the atmospheric CO2
concentration increased significantly from
≈ 270 μmol/ mol to current concentrations
greater than 385μmol/mol (Intergovernmental
Panel Climate Change, 2007; Le Quéré et al.,
2009; reviewed by Mittler and Blumwald, 2010).
Elevated atmospheric CO2 generally increases
plant productivity and alters nutrient element
cycling. However, there is a report that experi-
mental CO2 enrichment in a sandy soil with low
organic matter content can cause plants to accu-
mulate contaminants in plant biomass, with
declines in the extractable contaminant element
pools in surface soils (Duval et al., 2011). Com-
bined ambient greenhouse gas concentrations
(including methane, ozone and nitrous oxide) are
now expected to exceed concentrations of
550μmol/mol by 2050 (Raven and Karley, 2006;
Brouder and Volenec, 2008). Moreover, atmo-
spheric temperature is rapidly being changed
with the climate change and global warming. To
this end, the Intergovernmental Panel Climate
Change (2007) has projected average annual
mean warming increases of 3–5°C in the next
50–100 years due to the increase in greenhouse
gases (reviewed by Mittler and Blumwald, 2010).
Seven percent of the electromagnetic radia-
tion emitted from the sun is in the UV range
(200–400nm). A great reduction in and modifi-
cation of UV radiation takes place as it passes
through the atmosphere. Radiation of range
200–280nm (UV-C radiation) is completely
absorbed by atmospheric gases, 280–320 nm
(UV-B radiation) is additionally absorbed by
stratospheric ozone (thus only a very small pro-
portion is transmitted to the earth’s surface);
whereas, the radiation of range 320–400 nm
(UV-A radiation) is hardly absorbed by ozone
(Frohnmeyer and Staiger, 2003). The depletion
of the stratospheric ozone layer is leading to an
increase in UV-B radiation reaching the earth’s
surface with serious implications for all living
organisms. In this context, the release of
anthropogenic pollutants such as chlorofluoro-
carbons has earlier been regarded as a major
factor contributing a decrease of about 5% in
ozone concentration observed during the last
50 years (Pyle, 1996). This has raised interest
in the possible consequence of increased UV-B
levels on plant growth and development and
the mechanisms underlying these responses
(Mackerness, 2000; Frohnmeyer and Staiger,
2003). Moreover, UV-B radiation has also been

Environmental Change, and Plant Amino Acids and their Derivatives 3
regarded as a key environmental signal that initi-
ates diverse responses in plants that affect
metabolism, development and viability. Many
effects of UV-B involve the differential regulation
of gene expression (Jenkins, 2009). Tropospheric
ozone (O3) is currently viewed as a widespread
and growing problem that suppresses crop pro-
ductivity. Being a strong oxidant, O3 can interact
with constituents of the apoplast to generate
ROS (Hasanuzzaman et al., 2012). The antioxi-
dant system in plant tissues plays an important
role in conferring plants’ tolerance to O3 expo-
sure (Tausz et al., 2007). This increase in UV radi-
ation is predicted to increase in the near future,
which may cause a negative impact on plants and
other biological organisms. Extended exposure
to UV-B radiation is especially harmful to plants
due to their requirement for light (Sinha et al.,
2003). It also increases ROS and causes oxidative
stress and hence the antioxidant defense under
UV-stress is a matter of concern (Hasanuzzaman
et al., 2012).
1.2.1 Environmental changes-accrued
anomalies-aggravation in plants –
Signiﬁcance of abiotic stresses
In the complex field environment with its
heterogenic conditions, global environmental
changes-mediated potential anomalies are fur-
ther aggravated with varied abiotic stress combi-
nations, all together severely impacting modern
agriculture (Witcombe et al., 2008; Mittler and
Blumwald, 2010) (Fig. 1.1). Drought, tempera-
ture extremes and saline soils are the most com-
mon abiotic stresses that plants encounter. Plant
life and primary productivity depend on water
availability. On earth, nearly 20% of the global
land surface is too dry to be cultivated and areas
under drought are already expanding and this is
expected to increase further (Burke et al., 2006).
In this context, among the most severe environ-
mental stresses, drought has been considered a
major constraint for plant productivity world-
wide causing great damage to rain-fed and irri-
gated farming (Sadat Noori et al., 2011). Drought
stress may lead to stomatal closure, which reduces
CO2 availability in the leaves and inhibits carbon
fixation, exposing chloroplasts to excessive exci-
tation energy, which in turn could increase
the generation of ROS and induce oxidative stress
(de Carvalho, 2008; Hasanuzzaman and Fujita,
2011).
Land degradation is a decline in land qual-
ity caused by human activities, has been a major
global issue since the 20th century and is
expected to remain high on the international
agenda in the 21st century (Eswaran et al.,
2001). Though land degradation is reflected in
an increasing use of fertilizers, and spreading
pests increases the use of expensive agricultural
chemicals, land salinization is one of the major
factors of land degradation. Globally, approxi-
mately 22% of agricultural land is saline (FAO,
2004). According to UNEP (2009), ≈ 950 million
ha of salt-affected lands occur in arid and semi-
arid regions, nearly 33% of the potentially
arable land area of the world. Additionally,
worldwide, some 20% of irrigated land
(450,000 km2) is salt-affected, with 2,500–
5,000 km2 of lost production every year as a
result of salinity (UNEP, 2009). Hence, salt
stress is becoming a major concern for crop pro-
duction as increased salinity of agricultural land
is expected to have devastating global effects,
resulting in up to 50% loss of cultivable lands
(Mahajan and Tuteja, 2005). In most of the
cases, the negative effects of salt stress are ionic
stress (Na+ and Cl–) and osmotic stress, which
interrupt many plant processes. Nutrient deple-
tion as a form of land degradation has a severe
economic impact at the global scale. Erosion is
very significant in land degradation where the
productivity of some lands has declined by 50%
due to soil erosion and desertification (FAO,
2004; Burke et al., 2006).
Heavy metal (HM) contamination of agri-
cultural soils has emerged as a major environ-
mental problem severely impacting both the
productivity of plants and the safety of plant
products as foods and feeds. Moreover, the
rapid increase in population together with
fast industrialization causes serious environ-
mental problems, including the production and
release of considerable amounts of HMs in
the environment (Hasanuzzaman and Fujita,
2012). There is enough evidence that exposure
of plants to excess concentrations of redox
active HMs results in oxidative injury (Sharma
and Dietz, 2008; Hasanuzzaman and Fujita,
2012). High temperature (HT) is another major

4 N.A. Anjum et al.
Fig. 1.1. Schematic representation of: (a) environmental change – biotic and abiotic stress factors
relatedness in terms of their cumulative negative impacts on plants, and (b) the signiﬁcance of amino
acids, peptides and amines in the control of plant adaptation/tolerance to environmental change, biotic and
abiotic stress factors and their cumulative positive impacts on plant growth, metabolism and productivity.
AMINO ACIDS PEPTIDES
AMINES
Environmental change
Impaired
plant growth, metabolism
and development
Biotic
and
abiotic
stress
factors
Drastic yield reduction
Biotic
and
abiotic
stress
factors
Improved
plant growth, metabolism
and development
Improved
yield
Improved plant stress
adaptation/tolerance
Modulation of plant
antioxidant defense
system components

environmental factor that often affects plant
growth and crop productivity and leads to sub-
stantial crop losses (Hasanuzzaman et al., 2012).
The cellular changes induced by HT include
responses that lead to the excess accumulation
of toxic compounds, especially ROS that cause
oxidative stress (Mittler, 2002; Suzuki and Mit-
tler, 2006). Low temperature (LT) conditions
aggravate the imbalance between light absorp-
tion and light use by inhibiting the activity of
the Calvin-Benson cycle and enhanced photo-
synthetic electron flux to O2 and the over-
reduction of the respiratory electron transport
chain that causes ROS accumulation during
chilling (Hu et al., 2008). In addition, the solu-
bility of a gas increases, which leads to a higher
[O2] and thus enhances the risk of increased
production of ROS (Guo et al., 2006).
In a recent review, Mittler and Blumwald
(2010) revealed that drought–heat, salinity–
heat, ozone–salinity, ozone–heat, nutrient
stress–drought, nutrient stress–salinity, UV–
heat, UV–drought, and high light intensity
combined–heat, drought, or chilling are the
stress interactions that have a deleterious effect
on crop productivity. On the contrary, drought–
zone, ozone–UV and high CO2 combined with
drought, ozone or high light are the environ-
mental interactions that do not have a deleteri-
ous effect on yield and could actually have a
beneficial impact on the effects of each other
(Mittler and Blumwald, 2010). The global chal-
lenge will be to devise and implement a sus-
tainable balance between meeting the food
security needs of the poor and minimizing
the impacts of environmental changes (IPEC,
2003). In this context, continued technological
developments have been anticipated to facili-
tate the adaptation of crops to changing envi-
ronments (Gregory et al., 2005).
Plants have evolved very clever and fascinat-
ing adaptive mechanisms at the cellular, organ
and whole plant level that together help them to
survive and produce under adverse conditions.
As said also above these varied environmental
unfavourable changes or environmental stress
factors may impact plants both individually and/
or more commonly, in combination. Therefore,
plant responses to these environmental insults
are dynamic and involve complex cross-talk
between different regulatory levels, including
adjustment of metabolism and gene expression
for physiological and morphological adaptation
(Ahuja et al., 2010; Krasenky and Jonak, 2012).
In this context, involvement of coordinated
adjustments of a large array of metabolic net-
works in the plant adaptation mechanisms is
known. Among those are metabolic networks
containing different amino acids as intermediate
metabolites, which either as themselves or incor-
porated into proteins, accumulate to high levels
in response to specific cues, or serve as precur-
sors for a large array of metabolites with multiple
functions. The following sections highlight amino
acids and their major derivatives, and critically
discuss their significance for adaptation/toler-
ance of plants under non-optimum growth condi-
tions.
1.3 Amino Acids
All organisms are constituted essentially by
proteins where these molecules are required by
living cells for the execution of diverse func-
tions as metabolic regulation, transport,
defence and catalysis. Chemically, proteins are
polypeptides of 50 or more amino acids where
they can be joined via amide bonds to give pep-
tides. Amino acids are biologically important
organic compounds made from amine (-NH2)
and carboxylic acid (-COOH) functional groups,
along with a side-chain specific to each amino
acid. The key elements of an amino acid are
carbon, hydrogen, oxygen and nitrogen. Plants
and bacteria synthesize all 20 common amino
acids. Mammals can synthesize about half;
the others are required in the diet (essential
amino acids). About 500 amino acids are known
(Wagner and Musso, 1983) which can be classi-
fied in many ways. Structurally they can be
classified according to the functional groups’
locations as alpha- (α-), beta- (β-), gamma- (γ-)
or delta- (δ-) amino acids; other categories
relate to polarity, acid/base/neutral and side-
chain group type (including aliphatic, acyclic,
hydroxyl or sulfur-containing, aromatic). In
the form of proteins, amino acids comprise
the second largest component other than water
of human muscles, cells and other tissues
(Latham, 1997).

6 N.A. Anjum et al.
Table 1.1. Summary of amino acid classiﬁcation.
Class Name of the amino acids
Aliphatic Glycine, Alanine, Valine, Leucine, Isoleucine
Hydroxyl or Sulfur-containing Serine, Cysteine, Threonine, Methionine
Cyclic Proline
Aromatic Phenylalanine, Tyrosine, Tryptophan
Basic Histidine, Lysine, Arginine
Acidic and their Amide Aspartate, Glutamate, Asparagine, Glutamine
1.3.1 Classiﬁcation of amino acids
Although there are many ways to classify amino
acids, these molecules can be assorted into six
main groups, on the basis of their structure and
the general chemical characteristics of their R
groups (Table 1.1; Figs 1.2–1.7).
In plants, nitrogen is first assimilated into
organic compounds in the form of glutamate,
formed from alpha-ketoglutarate and ammonia in
the mitochondrion. In order to form other amino
acids, the plant uses transaminases to move the
Fig. 1.2. Aliphatic amino acids (neutral non-polar amino acids).
Glycine Alanine Valine
Leucine Isoleucine
amino group to another alpha-keto carboxylic
acid. For example, aspartate aminotransferase
converts glutamate and oxaloacetate to alpha-
ketoglutarate and aspartate (Buchanan et al.,
2000). Other organisms too use transaminases
for amino acid synthesis. Nonstandard amino
acids are usually formed through modifications to
standard amino acids. For example, homocysteine
is formed through the transsulfuration pathway
or by the demethylation of methionine via the
intermediate metabolite S-adenosyl methionine
(BrosnanandBrosnan,2006,whilehydroxyproline

Fig. 1.3. Hydroxyl or sulfur-containing amino acids.
Serine Cysteine
Threonine Methionine
Fig. 1.4. Aromatic amino acids.
Phenylalanine Tyrosine
Tryptophan

8 N.A. Anjum et al.
is made by a posttranslational modification
of proline (Kivirikko and Pihlajaniemi, 1998).
Because of their biological significance, amino
acids are important in nutrition and are com-
monly used in nutritional supplements, fertilizers
and food technology. Industrial uses include the
production of biodegradable plastics, drugs and
chiral catalysts.
A number of processes of nitrogen assimila-
tion, associated carbon metabolism, photorespi-
ration, export of organic nitrogen from the leaf
and the synthesis of nitrogenous end-products
have been reported to revolve around a hub of
amino acids (Foyer et al., 2003). Moreover,
specific major amino acids or their relative ratios
have been considered as potentially powerful
markers for metabolite profiling and metabolomic
Fig. 1.5. Acidic and their amide amino acids.
approaches to the study of plant biology (Foyer
et al., 2003).
1.4 Amino Acid Derivatives
In layman’s language, an amino acid derivative
is a molecule that is generated using an amino
acid as a starting point (precursor). It is impor-
tant to emphasize here that apart from an
amino acid’s significance as a vital component of
the protein synthesis, these compounds also
serve as precursors for a large array of amino acid
derivatives with multiple functions in plant
growth, development and response to various
stresses (Less and Galili, 2008).
Aspartate Glutamate
Asparagine Glutamine

A credible number of reports and reviews
have evidenced an extensive shift in plant metab-
olism, including metabolic networks associated
with amino acids as stressed plants’ adaptive/
survival strategy (Galili et al., 2001; Amir et al.,
2002; Galili, 2002; Stepansky and Galili, 2003;
Less and Galili, 2008). In this perspective, specific
amino acids (such as asparagine, histidine, pro-
line and serine) and peptides (such as gluta-
thione (GSH), phytochelatins (PCs)) (Sharma and
Dietz, 2006; Krasensky and Jonak, 2012), and
the amines (such as spermine, spermidine,
putrescine, nicotianamine and mugineic acids)
(Sharma and Dietz, 2006; Gill and Tuteja, 2010a;
Anjum et al., 2010, 2012a,b) have been exten-
sively reported and reviewed for their involve-
ment in plant stress tolerance. Additionally,
Fig. 1.6. Basic amino acids.
Histidine Lysine
Arginine
Fig. 1.7. Cyclic amino acid.
Proline

10 N.A. Anjum et al.
aromatic amino acids have extensively been evi-
denced as precursors for numerous metabolites,
such as hormones, cell wall components and a
large group of multiple functional secondary
metabolites (Radwanski and Last, 1995; Witt-
stock and Halkier, 2002; Pichersky et al., 2006;
Tempone et al., 2007; cited in Less and Galili,
2008). Amir et al. (2002), Wittstock and Halkier
(2002), Rebeille et al. (2006), Goyer et al. (2007)
evidenced Met to provide a methyl group to DNA
methylation, chlorophyll biosynthesis and cell
wall biosynthesis. Moreover, these authors have
also reported the significance of Met as a precur-
sor for the synthesis of the hormone ethylene,
polyamines and cellular energy glucosinolates. To
the other, Jander et al. (2004) and Joshi et al.
(2006) reported the involvement of Thr conver-
sion into Gly in seed development; while Mooney
et al. (2002) evidenced Ile catabolism-mediated
production of cellular energy.
Cysteine (Cys) is a sulfur-containing amino
acid and a central precursor of all reduced sulfur-
containing organic molecules including the
amino acid methionine (Met), proteins, vitamins,
cofactors (e.g. S-adenosylmethionine, SAM), mul-
tiple secondary metabolites and peptides (e.g.
glutathione, phytochelatins) significant for plant
biotic-abiotic stress tolerance and/or adaptation.
Hence because of its prominent tasks performed
(in conjunction with Met), Cys has now been
considered essential for the entire biological
kingdom. Proline is a proteinogenic amino acid,
contains a secondary amino group, has cyclic
structure, a restricted conformational flexibility
and stabilizes or destabilizes protein conforma-
tion secondary structures. Vital roles of Cys, GSH
and PCs for plant stress tolerance are credibly
available in literature (Cobbett, 2000, 2003; Hall,
2002; Heiss et al., 2003; Landberg and Greger,
2004; Sharma and Dietz, 2006; Anjum et al.,
2010, 2012a,b).
γ-aminobutyric acid (GABA) is a non-protein
amino acid. Apart from GABA significance for in-
plant metabolism (including carbon–nitrogen
metabolism, energy balance, signalling and devel-
opment), its rapid accumulation to high levels in
plants under different adverse environmental
conditions has been reported (Kinnersley and
Turano, 2000; Kaplan and Guy, 2004; Kempa
et al., 2008; Renault et al., 2010; Krasensky and
Jonak, 2012; Seher et al., 2013). Amino acids and
derivatives are able to chelate metals conferring
to plants resistance to toxic levels of metal ions.
Histidine consists of carboxyl, amino and imidaz-
ole groups and is considered the most important
free amino acid in heavy metal metabolism in
plants where it acts as a versatile metal chelator
and confers metal tolerance (Kramer et al., 1996;
Callahan et al., 2006). Nicotianamine (NA) is an
amino acid derivative, it occurs in all plants, is
involved in the movement of micronutrients in
plants (Stephan and Scholz, 1993) and chelates
Fe, Cu and Zn in complexes (Stephan et al., 1996)
and then accumulates within vacuoles (Pich
et al., 1997).
Increasing evidence suggests that osmopro-
tectants (osmolytes, compatible solutes) play
multiple critical roles in increasing plant toler-
ance to the abiotic stress factors. Osmoprotec-
tants occur in all organisms from bacteria to
higher plants and animals. These solutes of low
molecular weight are non-toxic even at high con-
centrations and are able to stabilize proteins and
cellular structures and/or to maintain cell turgor
by osmotic adjustment, and redox metabolism to
remove excess levels of ROS and re-establish the
cellular redox balance (Krasenky and Jonak,
2012). The accumulation of osmoprotectants
under abiotic stress differs among plant species
and chemically, these are of three types: betaines
and related compounds; amino acids, such as pro-
line, ecotine and their derivatives and polyols and
sugars, such as fructans, trehalose, mannitol, sor-
bitol, onoitol and pinitol. In plant cells, osmopro-
tectants are typically confined mainly to the
cytosol, chloroplasts and other cytoplasmic com-
partments that together occupy 20% or less of
the volume of mature cells (the other 80% is the
large central vacuole) (Rhodes and Samaras,
1994). The free amino acid proline is considered
to act as an osmolyte, a ROS scavenger and a
molecular chaperone stabilizing the structure of
proteins, thereby protecting cells from damage
caused by adverse environmental conditions such
as drought, high salinity or low temperatures
(Rontein et al., 2002; Sleator and Hill, 2002;
Verbruggen and Hermans, 2008; Szabados and
Savoure, 2010; Krasensky and Jonak, 2012).
Glycine betaine (GB) [(CH3)3N+CH2COO−], a qua-
ternary ammonium compound, is a very effective
osmoprotectant, which is naturally synthesized
and accumulated in response to various abiotic

stresses by plants, animals and bacteria (Chen
et al., 2000; Zhang et al., 2009). GB has been
reported to protect higher plants against salt/
osmotic stresses by maintaining osmotic adjust-
ment (Pollard and Wyn Jones, 1979; Jagendorf
and Takabe, 2001), protecting the photosystem II
(PSII) complex by stabilizing the connection of
extrinsic PSII complex proteins in the presence of
salt or under extremes of temperature or pH, and
also by protecting membranes against heat-
induced destabilization and enzymes such as
Rubisco against osmotic stress (Jolivet et al.,
1982; Murata et al., 1992; Mohanty et al., 1993;
Makela et al., 2000; Chen and Murata, 2011).
Polyamines (PA) stand second to none
among amine osmoprotectants and in terms of
their significance in plant stress tolerance and/or
adaptation. PA are small aliphatic molecules posi-
tively charged at cellular pH. The protonated
amino and imino groups in polyamines have a
positive charge that allows electrostatic interac-
tions with negatively charged groups in macro-
molecules and cellular substructures, providing a
stabilizing effect. Putrescine, spermidine and
spermine are the most common PAs in higher
plants. Various stresses, such as drought, salinity
and cold, modulate PA levels, and high PA levels
have been positively correlated with stress toler-
ance; where PA have been implicated in protect-
ing membranes and alleviating oxidative stress
(Groppa and Benavides, 2008; Alcazar et al.,
2011; Hussain et al., 2011; Krasenky and Jonak,
2012; Marco et al., 2012). Additionally, reports
suggest that electrostatic interactions of poly-
amines with phosphoric acid residues in DNA,
uronic acid residues in the cell wall matrix, and
negative groups on membrane surfaces help
maintain their functional and structural integrity
(Edreva et al., 2007; Marco et al., 2012).
The accumulation of carbohydrates (such as
starch and fructans) has been reported in plants
as ‘storage substances’ that are mobilized during
periods of limited energy supply or enhanced
energetic demands (Hendry, 1993). Carbohy-
drates such as mannitol, sorbitol, inositol and
fructans play an important role in osmoprotec-
tion. They stabilize membranes, subcellular com-
ponents, protein complexes or enzymes, preserve
dry membranes, liposomes and labile proteins
and protect them by ROS scavenging in plants
under varied abiotic stresses including drought
and salinity (Tuteja and Sopory, 2008; Valluru
and Van den Ende, 2008; Livingston et al., 2009).
Fructans exhibit high water solubility and are
resistant to crystallization at freezing tempera-
tures; therefore, fructan synthesis is very impor-
tant normally under low temperatures (Vijn and
Smeekens, 1999; Livingston et al., 2009), where
these compounds can stabilize membranes
(Valluru and Van den Ende, 2008) and/or may
indirectly contribute to osmotic adjustment upon
freezing and dehydration by the release of hexose
sugars (Spollen and Nelson, 1994; Olien and
Clark, 1995). Mannitol, a six-carbon non-cyclic
sugar alcohol, is the most widely distributed
sugar alcohol in nature and has been reported in
4100 species of vascular plants of several fami-
lies, including the Rubiaceae (coffee), Oleaceae
(olive, privet) and Apiaceae (celery, carrot, pars-
ley) where it acts as storage of carbon and
energy and helps in regulating coenzymes,
osmoregulation and free-radical scavenging
(Stoop et al., 1996; Bohnert and Jensen, 1996;
Prabhavathi and Rajam, 2007). The non-
reducing disaccharide trehalose accumulates to
high amounts in some desiccation-tolerant
plants. Trehalose accumulation in plants has
been reported only in Selaginella lepidophylla
(Adams et al., 1990) and Myrothamnus flabellifo-
lia (Bianchi et al., 1993). At sufficient levels, tre-
halose can function as an osmolyte and stabilize
proteins and membranes (Paul et al., 2008). The
accumulationofraffinosefamilyoligosaccharides
(RFOs) (such as raffinose, stachyose and verbas-
cose) has been reported in plants during seed
desiccation (Peterbauer and Richter, 2001) and
in leaves of plants experiencing environmental
stress like cold, heat, drought or high salinity;
where RFOs have been implicated in membrane
protection and radical scavenging (Hincha,
2003; Nishizawa et al., 2008; reviewed by
Krasenky and Jonak, 2012).
Nitrogen (alkaloids, cyanogenic glucosides
and non-protein amino acids) and sulfur (GSH,
glucosinolates, phytoalexins, thionins, defensins
and allinin) containing secondary metabolite
compounds are synthesized principally from
common amino acids (Rosenthal and Berenbaum,
1992; Van Etten et al., 2001). These compounds
have been linked directly or indirectly with the
defence of plants against biotic and abiotic stress
factors.

1.5 Conclusions and Perspectives
Life on earth relies directly or indirectly on plants
where humans harness them for food, feed, fibre,
fuel and fun. Food production and environmental
conditions are intricately linked; where growing
demands for food in turn affect the global envi-
ronment in many ways. Global food security has
been projected to face a severe threat from global
environmental change which includes naturally
or human activities-inﬂuenced changes in the
physical and biogeochemical environments. Nev-
ertheless, in the complex field environment with
its heterogenic conditions, global environmental
changes-mediated potential anomalies are fur-
ther aggravated with varied abiotic stress combi-
nations, all together severely impacting modern
agriculture. Being sessile in nature, plants, in a
variably changing environment, have to cope
with a plethora of adverse growth conditions
(hereafter called stress) where the majority of
these conditions can delay growth and develop-
ment and most importantly prevent them reach-
ing their full genetic potential in terms of
productivity. Employing multiple highly regu-
lated and interwoven metabolic networks, plants
exposed to stress factors often synthesize a set
of diverse metabolites that accumulate to con-
centrations in the millimolar range, particularly
specific amino acids (such as asparagine, histi-
dine, proline and serine), peptides (such as gluta-
thione and phytochelatins), and the amines
(such as spermine, spermidine, putrescine,
nicotianamine and mugineic acids). A credible
number of studies have shown significant
changes in the contents of the majority of amino
acids, peptides and amines thus indicating their
functional significance in the context of stress
tolerance and/or adaptations.
In the current volume, most of the high-
lighted above aspects will be covered in significant
contributions from renowned experts and
researchers working directly or indirectly on the
themeofPlantAdaptationtoEnvironmentalChange:
SignificanceofAminoAcidsandtheirDerivatives. The
outcome of the deliberations will help improve
crop tolerance to rapidly mounting varied stress
factors; hence to sustainably achieve enough food
to feed burgeoning world population.
Acknowledgements
NAA is grateful to the Portuguese Foundation
for Science and Technology (FCT) (SFRH/BPD/
64690/2009; SFRH/BPD/84761/2012) and the
Aveiro University Research Institute/Centre for
Environmental and Marine Studies (CESAM) for
partial financial support. IK is indebted to the
Portuguese Foundation for Science and Technol-
ogy (FCT) (SFRH/BPD/76850/2011). SSG and
RG would like to acknowledge the receipt of
funds from DBT, DST and UGC, Government of
India, New Delhi.
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© CAB International 2014. Plant Adaptation to Environmental Change
18 (eds N.A. Anjum, S.S. Gill and R. Gill)
2 5-Aminolevulinic Acid (5-ALA) – A
Multifunctional Amino Acid as a Plant
Growth Stimulator and Stress
Tolerance Factor
Yoshikatsu Murooka1* and Tohru Tanaka2
1Emeritus Professor of Osaka University, Takaya, Higashi-Hiroshima
739-2125, Japan; 2SBI Pharmaceuticals Co., Ltd., 1-6-1 Roppongi,
Minato-ku, Tokyo 106-6017, Japan
2.1 What is 5-Aminolevulinic Acid?
5-Aminolevulinic acid (5-ALA) is the abbrevia-
tion for 5-Amino Levulinic Acid, which was
thought to be born on primitive earth 3.6 billion
years ago. In all living organisms including micro-
organisms, plants and animals, 5-ALA is the first
stable intermediate in the biosynthesis pathway
of tetrapyrrole compounds such as heme, chloro-
phylls (Lascelles, 1960) and vitamin B12 (Sato
et al., 1981). Thus, 5-ALA is an essential and
bottleneck compound in living organisms. Eight
molecules of 5-ALA form a ring and become por-
phyrin which can store the energy of sunlight
(Fig. 2.1).
2.2 Biosynthetic Pathway of
5-Aminolevulinic Acid
5-ALA is synthesized via either the C4 (Shemin)
pathway in which 5-ALA is formed by ALA syn-
thase (ALAS) from succinyl CoA and glycine
or the C5 pathway, which uses the intact C5
skeleton of glutamic acid as a substrate via gluta-
myl tRNA and glutamyl 1-semialdehyde (GSA),
and then the GSA is converted to 5-ALA by GSA
2-aminotransferase (HemL) (Nishikawa and
Murooka, 2001).
2.2.1 Microorganisms
ALAS (EC 2.2.1.37) in the C4 pathway is encoded
by the hemA gene, which was cloned from various
organisms including Rhizobium meliloti (Leong
etal.,1985),Bradyrhizobiumjaponicum(Robertson
McClung et al., 1987), Rhodobacter capsulatus
(Hornberger et al., 1990) and R. sphaeroides (Nee-
dle and Kaplan, 1993).
In the C5 pathway, organisms require three
genes, gltX, hemA (different from the hemA gene
in the C4 pathway) and hemL for 5-ALA synthesis.
The gene encoding ALA synthesis (hemA) through
the C5-pathway was also cloned from Escherichia
coli (Li et al., 1989; Verkamp and Chelm, 1989;
Ikemi et al., 1992), Bacillus subtilis (Hansson
et al., 1991), Salmonella typhimurium (Elliott et al.,
1990) and Xanthomonus campestris pv. phaseoli
* Corresponding author, e-mail: murooka@bio.eng.osaka-u.ac.jp

5-ALA – A Multifunctional Amino Acid and Plant Growth Stimulator 19
(Asahara et al., 1994). The hemL gene was cloned
from E. coli (Ilag et al., 1991; Grimm et al., 1991),
Synechococcus sp. (Grimm et al., 1991), Propioni-
bacterium freudenreichii (Murakami et al., 1993a)
and X. campestris pv. phaseoli (Murakami et al.,
1993b).
2.2.2 Higher plants
The customary route in animals and bacteria for
5-ALA biosynthesis was from glycine and succi-
nyl CoA, catalysed by the enzyme ALA synthe-
tase. Attempts to demonstrate this route in
plants was unsuccessful. Evidence was given for
a new enzymatic route of synthesis of 5-ALA in
plants. In greening higher plants, Beale and
Castelfranco (1974) found that tissues pos-
sessed an alternative route to 5-ALA in which
the five carbon skeleton of glutamate (and alpha-
ketoglutarate) was incorporated intact into the
first committed metabolite of the chlorophyll
pathway (Beale et. al., 1975). In etiolated leaves
in the dark, both the succinyl CoA-glycine path-
way and the 5-carbon pathway contribute to
5-ALA biosynthesis (Meller and Gassman,
1982). From the study of the stimulatory effect
of cytokine, benzyladenine, on the synthesis of
5-ALA in cucumber, the stimulation of 5-ALA by
benzyladenine was due to an increased level of
tRNAGlu in plastids.
Thus, depending on the organisms, 5-ALA is
made either by a C-5 pathway or by a C-4 pathway
(Avissar et al., 1989). In Euglena gracilis, both C-4
and C-5 pathways of 5-ALA synthesis were
reported (Weinstein and Beale, 1983).
2.3 Chemical Synthesis of
5-Aminolevulinic Acid
5-ALA is synthesized chemically via selective
reduction of acyl cyanide (Pfaltz and Anwar,
1984) or via dye-sensitized oxygenation of
Fig. 2.1. Alternative pathway of 5-ALA biosynthesis and biosynthetic pathway of tetrapyrrole derivatives
from 5-ALA. 5-ALA is synthesized via either the C4 pathway (Shemin pathway) or the C5 pathway. 5-ALA
is a precursor of vitamin B12, heme and chlorophylls. Genes involved in these metabolic pathways are
explained in text.
C5 pathway
COOH
COOH
COOH
COOH
COOH COOH
COOH
COOH
COOH
COOH
COOH
COOH
COOH
COOH CHO
HOOC
HOOC
COOH
S
O
CoA
NH2
NH2
NH2
NH2
NH2
O
H2
N
N
H
tRNA glu
O
gltX
hemL
hemC hemD Uroporphyrinogen
III
N
NH
HN
N
Hemes
Chlorophylls
Glutamate-1-semialdehyde
Porphobilinogen
(PBG)
Glutamic acid
Glutamyl-tRNA
Succinyl-CoA Glycine
hemB
hemA
hemEFGHN
C4 pathway
(Shemin pathway)
Vitamin B12
5-Aminolevulinic acid
(5-ALA)
hemA cobA
cbiLEGHF
cobUS

20 Y. Murooka and T. Tanaka
N-furfurylphthalimide (Takeya et al., 1996).
However, the chemical synthesis of 5-ALA
requires at least four reaction steps and the yield
was less than 60%. Typical examples of 5-ALA
chemical syntheses are shown in Fig. 2.2. The
high cost of chemical production of 5-ALA, ten
times more expensive than gold, has thus far lim-
ited its commercial utilization.
2.4 Biosynthetic Pathway
of Tetrapyrrole Compounds
from 5-Aminolevulinic Acid
Porphyrin is biosynthesized from 5-ALA and acts
as an important cofactor in both plant and animal
cells. Various metals are inserted into porphyrin
and show many functions.
2.4.1 Monopyrrole porphobilinogen and
urogens from 5-aminolevulinic acid
The 5-ALA is dimerized into the monopyrrole
porphobilinogen (PBG) catalysed by ALA dehy-
dratase (or PBG synthase, EC 4.2.1.24) encoded
by hemB (Fig. 2.1). ALA dehydratases in organ-
isms range in size between 250 and 340kDa.
Those from E. coli (Spencer and Jordan, 1993),
P. freudenreichii (Hashimoto et al., 1996) and
animal cells (Wu et al., 1974) consist of homo-
octomer subunits, whereas those from R. sphaer-
oides (Heyningen and Shemin, 1971) and higher
plants (Liedgens et al., 1980) are hexameric pro-
teins consisting of six identical subunits of
40kDa and 50kDa, respectively. The plant ALA
dehydratase utilizes Mg2+ or Mn2+ (Boese et al.,
1991), whereas animal cells and Saccharomyces
cerevisiae require Zn2+. E. coli and R. sphaeroides
N OH N OH
HO
N
H
O
O
OH
O
O
OR
O
O
Br
OH
O
O
H2
N
HO
OH
O
O
Cl
OR
O
O
NC
OR
O
O
N
O
O
O
N
O
O
O
OR
RO
Vis.Light
Sens.O2
83%
H2
5%-Pd/C
95%
HCl
65%
(A)
(B)
(C)
(D)
(E) N
O
O
O
N
O
O O
OH:Py
O
N
O
O O
OH:Py
O
H
2
N
O
OH
O
Fig. 2.2. Chemical synthesis of 5-ALA. (A) Herdeis and Dimmerling (1984); (B) MacDonald (1974); (C)
Suzuki, K. Japan Kokai Koho (Japanese patent no. Heisei 2-76841), 1990; (D) Pfaltz and Anwar (1984);
(E) Takeya et al. (1994).

require Mg2+ and K+ ions, respectively. This
enzyme is inhibited by levulinic acid, 4,6-
dioxyhepatonic acid or other 5-ALA analogues
(Nandi and Shemin, 1968; Luond et al., 1992).
PBG deaminase (hydroxymethylbilane syn-
thase or urogen I synthase; EC 4.3.1.8) encoded
by hemC, catalyses the tetra polymerization of
the preurogen PBG to yield the unstable hydroxy-
methylbilane. Urogen II synthase (EC 4.2.21.7.5)
encoded hemD subsequently catalyses the isom-
erization and cyclization of hydroxymethylbilane
to the key precursor, urogen III (uroporphyrino-
gen III) (Battersby and Leeper, 1990). In the pres-
ence of the urogen III synthase, preurogen
cyclizes chemically to give urogen I. Urogen III is
the first circular tetrapyrrole of the pathway and
the last intermediate that is common to all end
products (Fig. 2.1).
2.4.2 Vitamin B12 biosynthesis
The pathways leading to vitamin B12 and siroheme
branch off from the common tetrapyrrole pathway
at urogen III (uroporphyrinogen III). In P. freuden-
reichii, hemYHBXL gene cluster, which encodes
enzymes and regulator involved in the biosyn-
thetic pathway from glutamate to protoheme, was
isolated by Hashimoto etal.(1996, 1997) (Fig. 2.1).
Most of the steps and encoding genes to bio-
synthesize vitamin B12 have been characterized
in Pseudomonas denitrificans (Blanche et al.,
1995), Salmonella typhimurium (Roth et al., 1993;
Raux et al., 1996) and P. freudenreichii (Sattler
et al., 1995; Roessner et al., 2002; Piao et al.,
2004a, 2004b; Murooka et al., 2005). The biosyn-
thesis from uroprophyrinogen III to form precor-
rin-2 is catalysed by CobA, three gene products,
CysG, CbiK and CbiX, and at least 13 gene prod-
ucts, CbiL, CbiEGH, CbiF, CbiJ, CbiC, CbiA, CbiP,
CbiT, CobT, CobD, CobC, CobU and CobS involved
in the synthesis of adenosylcobalamin (vitamin
B12) (Murooka et al., 2005).
2.4.3 Biosynthetic regulation
of chlorophyll and heme
In photosynthetic organisms, biosyntheses of
chlorophyll and heme are tightly regulated at
various levels in response to environmental
adaptation and plant development. Bacteriochlo-
rophyll formation by enzymes was studied in
growing cultures of R. sphaeroides (Lascelles,
1960). The formation of 5-ALA is also the key
regulatory step in higher plants and provides
adequate amounts of the common precursor mol-
ecule for the Mg and Fe branches of tetrapyrrole
biosynthesis. Control of chlorophyll synthesis was
proposed by Nadler and Granick (1970), based on
a light-induced activation at the translational level
of the synthesis of proteins forming 5-ALA, as
well as the short half-life of these proteins. A cor-
relation between down-regulated 5-ALA synthe-
sis and accumulation of protochlorophyllide and
rapid repression of 5-ALA synthesis were seen in
the dark (Richter et al., 2010). The biochemistry of
the pathway is well understood and almost all
genes encoding enzymes of tetrapyrrole biosyn-
thesis have been identified in plants. However, the
post-translational control and organization of the
pathway remains to be clarified. Post-translational
mechanisms controlling metabolic activities are of
particular interest since tetrapyrrole biosynthesis
needs adaptation to environmental challenges
(Czarnecki and Grimm, 2012).
2.5 Production
of 5-Aminolevulinic Acid
To accumulate 5-ALA by microorganisms, levu-
linic acid, an analogue of 5-ALA which is known
to be a competitive inhibitor of ALA dehydroge-
nase, is added to the fermentation process.
Glycine and succinate as precursors of 5-ALA for
the C-4 pathway are also added in the medium.
2.5.1 Microbial production
of 5-aminolevulinic acid
Many reports of production of 5-ALA by microor-
ganisms were published. These microorganisms
were Clostridium spp. (Koesnander et al., 1989),
Methanobacterium spp. (Jaenchen et al., 1981;
Gilles et al., 1983; Lin et al., 1989), Chlorella spp.
(Beale, 1971; Sasaki et al., 1995; Ano et al., 1999
and 2000), Propionibacterium spp. (Kiatpapan and
Murooka, 2001; Kiatpapan et al., 2011) and many
species of photosynthetic bacteria (Nishikawa
and Murooka, 2001).

For the production of 5-ALA, Rhodobacter
sphaeroides, a purple non-sulfur photoheterotro-
phic bacterium, requires light illumination and
addition of levulinic acid and obtained 4.2 ~ 15mM
5-ALA under the light illumination (Sasaki et al.,
1990, 1993), over double to five times that of
other 5-ALA producers such as Chlorella regularis
(Ano et al., 2000).
Recombinant strains were also developed to
produce 5-ALA with cloned the hemA gene which
encodes ALA synthase. Van der Mariet and
Zeikus (1996) succeeded in producing up to
20mM 5-ALA by cell extracts of recombinant
E. coli carrying R. sphaeroides hemA. However, this
enzymatic conversion requires the addition of a
large amount of ATP to supply succinyl-CoA to
the reaction. Recombinant Propionibacterium was
also constructed by transfer of an expression
vector pPK705 carrying the hemA gene from
R. sphaeroides and obtained 8.6mM 5-ALA in
the presence of levulinic acid (Kiatpapan and
Murooka, 2001).
2.5.2 Industrial strains development for
5-aminolevulinic acid overproduction
Production of 5-ALA by photosynthetic bacteria
required light irradiation and addition of levu-
linic acid both of which are significantly costly. In
R. sphaeroides, 5-ALA production was inhibited
by aeration or agitation and also yeast extract,
which required the cell growth and inhibited
secretion of 5-ALA. Thus, we tried to breed
improved strains, which can overproduce 5-ALA
in the absence of light and under aerobic condi-
tion with yeast extract, by sequential mutations
(Nishikawa et al., 1999). Finally we succeeded in
obtaining an industrial strain selected from more
than 80,000 mutants that can overproduce
5-ALA more than 30mM under dark aerobic
conditions and in inexpensive culture medium
(Kamiyama et al., 2000; Nishikawa and Murooka,
2001). The process of these sequential mutations
is summarized in Fig. 2.3.
Like several essential amino acids, 5-ALA
can be produced by fermentation with the photo-
synthetic bacterium that has advantages for its
purity, safety, non-GMO and cost competitive-
ness in comparison with the products available
on the market.
2.6 Biological Activity
of 5-Aminolevulinic Acid
5-ALA is a key precursor in the biosynthesis of
chlorophyll. Its versatile use in horticulture is
gaining more attention. 5-ALA has several
biological activities as follows: (i) a common
precursor of tetrapyrrole compound in all living
organisms; (ii) a biodegradable herbicide; (iii) an
insecticide; (iv) a plant growth hormone;
(v) improving stress resistance for plants; (vi) a
photodynamic cancer therapy; and (vii) a supple-
ment for human and animal health. In high con-
centrations above 1000ppm, 5-ALA acts as an
herbicide. In contrast, when used in low concen-
trations between 1 and 100ppm, 5-ALA has ben-
eficial effects on the growth of crops. These include
improvements in dry matter yield, positive effects
on photosynthetic activity and inhibitory effects
on respiration. In addition to these advantages,
increased salt tolerance, cold tolerance and other
environmental stress tolerance of crops were
observed in the presence of 5-ALA.
2.6.1 Herbicide and insecticide
5-ALA activates the chlorophyll biosynthetic
pathway. 5-ALA treatment of higher plants at
high concentrations (i.e. more than 10mM) gives
rise to harmful effects whereby excess accumula-
tion of several chlorophyll intermediates, such
as protochlorophyllide and protoporphyrin IX
occurs in the dark (Granick, 1959; Sisler and
Klein, 1963; Nadler and Granick, 1970). During
the subsequent light period the accumulated tet-
rapyrroles act as potent photodynamic sensitiz-
ers,whichinturnresultinthedeathofsusceptible
plants. The accumulated chlorophyll intermedi-
ates act as photosensitizer for the formation of
active oxygen, triggering photodynamic damage
of 5-ALA-treated plants (Askira et al., 1991;
Chakraborty and Tripathy, 1992). 5-ALA is effec-
tive against dicotyledonous weed species such as
mustard, red-root pigweed, common purslane
and lambsquarters which are susceptible to the
light, while monocotyledonous plants such as
corn, wheat, barley and oats are not (Rebeiz et al.,
1984, 1990; Kittsteiner et al., 1991). These obser-
vations seem to use 5-ALA as a photodynamic
herbicide (Sasikala et al., 1994).

As a photodynamic insecticide, 5-ALA was
also reported by Rebeiz et al. (1988). When 5-ALA
itself or combined with 2,2’-dipyridyl was sprayed
on the larvae of Trichoplusiani insects accumu-
lated protoporphyrin IX, causing death in dark-
ness and in light. They propose the term
‘porphyric insecticides’ to designate such insecti-
cides. The porphyrin insecticides may reside in
the potential to design a large number of totally
biodegradable formulations that can act as selec-
tive photodynamic insecticides and herbicides
and also in the anticipated difficulty for insects to
develop resistance towards such insecticides.
2.6.2 Plant growth stimulation
by 5-aminolevulinic acid
Although 5-ALA treatment of higher plants at
high concentrations injures the plants, Hotta
et al. (1997b) found that a low concentration of
5-ALA with minerals, such as Mg and Fe, had
promotive effects on the growth and yield of
several crops and vegetables at concentrations
less than 1.8mM by foliar spray and 60μM by
root-soaking. The appropriate applications of
5-ALA showed 10% to 60% promotive effects
over the control for radishes, kidney beans,
barley, potatoes, garlic, rice and corn (Hotta et al.,
1997a). These promotions of plant growth were
observed in light, but did not affect those in
darkness. 5-ALA at 0.06μM elicited the accumu-
lation of chlorophyll, but the photosynthesis of
the plants was promoted by treatment together
with 5-ALA and nutrients. Castelfranco et al.
(1974) found that exogenous 5-ALA treatment
resulted in the abortion of the lag phase in
greening cucumber cotyledons. The application of
a low concentration of 5-ALA by foliar spray
increased fixation of CO2 in light and suppressed
release of CO2 in darkness (Hotta et al., 1997a).
These results suggest that 5-ALA has a variety
of plant physiological effects on chlorophyll
synthesis, photosynthesis and plant growth, and
5-ALA acts as a growth regulator in plants at
low concentrations. These effects of 5-ALA were
assumed to be linked to light irradiation and
an uptake of fertilizer by plants. 5-ALA also
enhances nitrate and nitrite reductase activities
that contribute to the decrease in NO3-N con-
centration by supplying a large amount of
α-ketoglutaric acid (Mishira and Srivastava,
1983; Yoshida et al., 1993).
Mutant
strain
Rhodobacter sphaeroides CR-001 (IFO12203)
5-ALA
(mM)
Oxygen resistant
1/5,000 (establish bioassay system for 5-ALA)
(0.25) CR-286 Produce 5-ALA with 0.1% yeast ext.
1/10,000 (micro titre plate screening)
(1.5) Produce 5-ALA without light
1/10,000 (TCL plate screening)
(3.8) Cut a bi-product, aminoacetone
(8.1) Produce 5-ALA with low conc. levulinic acid
(11.2) CR-606 Nishikawa et al. (1999)
(>30) Stable, industrial strain
CR-105
CR-386
CR-450
CR-520
CR-720
Fig. 2.3. Sequential mutations to overproduce 5-ALA from Rhodobacter sphaeroides CR-001
(IFO12203). Each CR mutant strain was selected from approximate colony numbers indicated. The
method of selection is shown in parentheses. Levels of 5-ALA production in each strain in basal medium
containing yeast extracts under agitation in the dark (test tube). Appropriate concentration of levulinic
acid was also added in the medium for the 5-ALA production test (Nishikawa et al., 1999).

Figure 2.4 shows the test of greening of
pothos lime leaves by a spray of between 0.1ppb
and 1.0ppm 5-ALA and showed most greening of
leaves at the concentration of 1ppb to 10ppb.
Regarding photosynthetic activity in a chamber,
the same increasing effect of photosynthesis was
obtained, such as widening the opening of an
air-hole. Figure 2.5 shows photosynthetic activity
and dark respiration of manila grass (Zoysia
matrella Merr.) with the same 5-ALA treatment
(Hotta et al., 2000). Regardless of the fact that
photosynthesis was increased due to 5-ALA treat-
ment, the level of dark respiration was decreased.
Since 5-ALA is an intermediate not only for
chlorophyll but also for heme, in particular for
cytochrome, by increasing cellular cytochrome
activity derived from 5-ALA, energy acquisition
could get easier, which results in decreased
respiration.
When miniature roses were placed in the
dark they did not perform sufficient photosyn-
thesis, and dropped yellow leaves as control (Fig.
2.6). After treatment with a low concentration
of 5-ALA, they were capable of photosynthesis
under low light intensity that resulted in contin-
uation of their normal growth without losing
their leaves.
The effect of 5-ALA on growth of Liliaceous
root vegetables, such as garlic, is prominent.
5-ALA improvements to produce larger sized gar-
lic bulbs not only correspond to increased yield
per area, but also an upgrade in quality (Fig. 2.7).
5-ALA treatment at 250ppm significantly
improved the net photosynthetic rate of pak choi
(Brassica campestris) resulting from enhancement
of syntheses of chlorophyll and antioxidative
enzymes, such as peroxidase, catalase and super-
oxide dismutase (Memon et al., 2009).
5-ALA also improved the growth and quality
of fruits, such as Vigna catjung, V. mungo, V. radi-
ata, (Roy and Vivekanandan, 1998) and grapes
(Watanabe et al., 2006). The photosynthetic rate
of grapevine treated with 5-ALA at 100ppm
(foliar treatment) and 1ppm (soil treatment)
increased by a significant 9.2 to 22.5% (Watanabe
et al., 2006). In terms of fruit quality, the cluster
fresh weight increased a significant 44.9–53%
Fig. 2.4. Effect of 5-ALA on greening of leaves
of pothos lime. 1 ppb to 1.0 ppm concentrations of
5-ALA were applied by foliar application.
5-ALA (ppm)
0 0.0001 0.001 0.01 0.1 1.0
Photosynthesis
160
140
120
100
(%)
80
60
160
140
120
100
(%)
80
60
0 1 3
Day(s)
7 14 0 1 3
Day(s)
7 14
Respiration
Control + 5-ALA Control + 5-ALA
(A) (B)
Fig. 2.5. Effect of 5-ALA on photosynthetic activities of manila grass grown under light illumination (A)
and dark (B) conditions (Hotta et al., 2000).

Control Fertilizer +0.1ppm 5-ALA +1ppm 5-ALA
1 week
2 weeks
3 weeks
Fig. 2.6. Effect of 5-ALA on prevention of dead leaves of miniature roses grown under low light
conditions. 0.1 to 1 ppm 5-ALA in the basal medium was treated on soil cultivating miniature roses.
5-ALA (0 ppm) 5-ALA (30 ppm) 5-ALA (100 ppm)
60
80
100
120
140
160
5-ALA conc. (ppm)
100
138 139
0
(%)
30 100
29.4g
Fig. 2.7. Effect of 5-ALA on yield of garlic (Liliaceous root vegetable). 5-ALA was applied by foliar application.

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