This presentation was being presented by Etalesh Goutam (M.Sc. Horticulture; 2018-2020) in the master seminar at Department of Horticulture, H.N.B. Garhwal University, Srinagar (Garhwal) Uttarakhand- 246174

2. MASTER SEMINAR (SOA/HC-514)
PRESENTATION
ON
Improvement Of Horticultural Crops For
Abiotic Stress Tolerance
Presented By: EtaleshGoutam
Enroll. Number: G181342631
H.N.B. GARHWAL UNIVERSITY (A CENTRAL UNIVERSITY)
SRINAGAR (GARHWAL), UTTARAKHAND- 246174
SEMINAR IN CHARGE: DR. D.K. RANA
(ASSIST. PROFESSOR)
(DEPARTMENT OF HORTICULTURE)

3. CONTENTS:
Introduction
Classification of Stress
Abiotic stress impact on plant physiology
Abiotic stress tolerance mechanism in plants
Improvement of Horticultural crops to abiotic stress tolerance
Conclusion
References

4. INTRODUCTION:
Earlier the improvement of horticultural crops has traditionally
focused on enhancing a plant’s ability to resist various biotic stresses.
Research on crop resistance or tolerance to abiotic stresses (heat, cold,
drought, flood, salt, pH, etc.) has not received much attention.
Abiotic stresses, such as adverse environmental conditions, can
strongly reduce crop performance, with crop yield losses ranging
from 50% to 70%.
There is a need to change the strategy for addressing abiotic stress in
horticulture through research, management, capacity building and
policy changes to promote innovative and rewarding technologies.

5. Scenario of Indian Horticulture (2019-20):
The scenario of horticultural crops in India has become very
encouraging. The percentage share of Horticulture output in Agriculture
has become 33%. Under the purview of Agriculture & Allied activities,
the share of plan outlay for Horticulture which was 3.9% during IX Plan,
has increased to 4.6% during the XII Plan. The total Horticulture
production has increased from 211.2 million MT in 2007-08 to 320.5
million MT in 2019-20 (NHB Data base 2019-20 II Advance estimate).

6. Abiotic stress and history:
The word ‘Stress’ was first introduced into the theory of elasticity as an
amount of force for a given unit area (Cauchy, 1821). Plant stress has been
defined by as ‘any unfavorable condition or substance that affects or blocks a
plant’s metabolism, growth or development’
It is any change in environmental conditions that might reduce or adversely
change a plant’s growth or development. Jacob Levitt is considered as the
‘Father of Plant Stress Physiology’ (Levitt,1980).

7. Abiotic stress toll on global economy:
Considering stress factors, drought and salinity are the most significant
issues threatening agricultural production on a global scale. It is estimated
that the total economic value of loss caused by drought and heat
globally is about 1.3 billion, and due to cold is about 18.6 million
[ICGEB].
According to plant molecular biologists at the International Centre for
Genetic Engineering and Biotechnology [ICGEB], New Delhi, soil
salinity and drought were the two major threats to the crops in India.
The International Crops Research Institute for Semi-Arid Tropics
[ICRISAT], currently located in Hyderabad, is actively involved in the
development of drought resistant transgenic and other economically
important plants. According to one study, nearly 24 percent of Indian
agricultural land has been damaged by salinity. This has fuelled scientific
manpower to evolve transgenic strategy to enhance plant productivity.

8. Classification of Stress:
Plate 1: Different types of stress

9. Abiotic stress impact on plant physiology:
Plate 2: Scheme of factors that determine crop response to abiotic stresses
(Source: Mariani et al., 2017)

10. Plate 3: Illustrating abiotic stress encountered symptoms in plant

11. Abiotic stress in relation to postharvest quality:
The quality of horticultural products is the result of the interaction of
different factors, including grower’s crop management ability, genotype, and
environment.
Plate 4: Abiotic factor consequences on postharvest quality

12. Plate 5: A schematic representation of response of plants towards abiotic stress
(Source: Francini et al., 2019)

13. Abiotic stress tolerance preferably commence
at two distinct level, such as-
A. Tolerance mechanism at molecular level:
It includes functioning at molecular to combat abiotic stressors.
B. Tolerance through endogenous hormonal balance:
Balance in the internal state of endogenous hormone also favour
the survival of plants with respect to encountering abiotic stresses.

14. A. Tolerance mechanism at molecular level:
Activation of signaling factors
 Altered gene expression
 Accumulation of compatible solutes
 Synthesis of stress proteins
 Enhanced anti-oxidative metabolism
 Ion homeostasis and compartmentation
 Facilitated membrane transport
 Accumulation of polyamines
B. Endogenous hormonal balance:
 Stress induces production of high ABA, low CK and Auxin and alter
GA and ethylene level.
 Increase in CK level- exceeding the pre stressed level cause
improvement in yield.
 Increased ABA during drought: induce cross tolerance. e.g.
salinity/cold tolerance.

15.  ABA mediated abiotic stress tolerance:
Plate 6: Vertical Flow Chart of ABA synthesis pathway
Plate 7: A diagrammatic view of new generation in PGRs

16. Improvement of Horticultural crops to abiotic
stress tolerance:
Approaches to improve abiotic stress tolerance:
1. Improvement of stress tolerance through plant genetic
engineering.
2. Improvement of stress tolerance through transgenic approach.
3. Improvement of stress tolerance through rootstock breeding.
4. Improvement of stress tolerance through protective molecules

17. A. Modification of plant architecture:
Zheng et al. (2001) ectopically expressed a tobacco phytochrome
B1 (PHY-B1) gene in ‘Iridon’ chrysanthemum under the control of
CaMV35S promoter to reduce plant height for the commercial
production of chrysanthemum.
B. Genome editing technology:
CRISPR/Cas9 editing tools have been efficiently applied in a
number of horticultural crops including tomato, petunia, citrus, grape,
potato and apple for gene mutation, repression, activation and
epigenome editing (Nishitani et al., 2016; Ren et al., 2016; Song et al.,
2016).
1. Improvement of stress tolerance through
plant genetic engineering:

18. Plate 8: Overview of various transgenic strategies targeting horticultural crop
improvement (Source: Parmar et al., 2017)

19. Plate 9: A general pathway from stress recognition to stress tolerance
through gene induction.

20. 2. Improvement of stress tolerance through
transgenic approach:
A) Marker-free transgenic technology:
De Vetten et al. (2003) suggested the use of marker-free gene construct for
genetic transformation of potato followed by polymerase chain reaction (PCR)-based
selection of transformed cells for identification of transformants. Co-transformation
with two gene constructs followed by segregation of marker gene and gene of
interest in segregating generation has been explored.
B)Trichoderma species as abiotic Stress reliever:
Trichoderma species, one of the most widely used microbes for the biocontrol
of plant diseases and also known to alter the response of plants to abiotic stresses.
Subsequently, isolation of genes from this biocontrol agent and their further transfer
to a plant genome may result in a significant improvement in plant tolerance to biotic
or abiotic stresses (Zaidi et al., 2014).

21. Crop
Gene and genetic
transformation
method used
Mechanism of action Trait improvement Reference
Apple
Osmyb4;
Agrobacterium
tumefaciens-mediated
gene transfer
A Myb family
transcription factor,
leads to accumulation
of various solutes
compatible to abiotic
stress tolerance
Enhanced tolerance to
drought and low temperature
stress
Pasquali et al.
(2008)
Banana
MusaWRKY71;
Agrobacterium
tumefaciens-mediated
gene transfer
Encodes a WRKY
transcription factor
Enhanced tolerance to
drought, salinity and high
temperature
Shekhawat
and
Ganapathi
(2013)
Table 1: Transgenic horticultural crops for abiotic stress
tolerance/management:
Chrysanthemu
m
(Chrysanthemu
m morifolium)
cv. ‘Jinba’
CmWRKY1
transcription factor
(derived from C.
morifolium);
Agrobacterium
tumefaciens-mediated
gene transfer
CmWRKY1 works as
positive regulator in
drought stress
The transgenic plants
displayed increased drought
tolerance
Fan et al.
(2016)

22. Tomato (Solanum
lycopersicum cv.
Aika Craig)
Sly-miR169c (an
miR169 family
member)
Agrobacterium
tumefaciens-mediated
gene transfer
Down regulates the
transcripts of target
genes namely; three
nuclear factor Y
subunit genes (S1NF-
YA1/2/3) and one
multidrug resistance-
associated protein
(slMRP1) gene
Enhanced drought tolerance
Zhang et al.
(2011a,
2011b)
Potato cv.
Superior
Cod A gene (from
Arthrobacter
globiformis);
Agrobacterium
tumefaciens-mediated
gene transfer
Cod A gene codes for
glycine betaine, which
scavenges oxidative
stress-inducing
molecule (free
radicals) and it also
protects the
photosynthetic system
The transgenic potato plants
displayed a stronger
antioxidant activity &
higher chlorophyll content
Cheng et al.
(2013)
Crop
Gene and genetic
transformation
method used
Mechanism of action Trait improvement Reference
Kiwi
AtNHX1 gene;
Agrobacterium
tumefaciens-mediated
gene transfer
Keeps K+/Na+ ratio
high during salinity
stress conditions
Enhanced tolerance to
salinity stress in transgenic
plants
Tian et al.
(2011)

23. 3. Improvement through rootstock breeding:
The use of rootstocks in horticultural production includes not only
limited to resistance against pathogens but also a higher tolerance to abiotic
stress conditions such as salinity, heavy metals, nutrient stress, water stress,
and alkalinity. There is extensive genetic diversity in rootstocks which
provides tolerance against these abiotic stress. So, Keeping in mind
challenges of environmental stresses and quality fruit production in stress
prone areas implication of rootstock breeding is really instrumental for
farmers.

24. Table 2: Abiotic stress tolerance through Rootstock breeding:
Improved trait Crop Rootstock used Reference
Drought tolerance
Plum Marianna GF 8-1 Wolfe et al., 2011
Peach Almond Wang, 1985
Cold tolerance
Apple G 11, G 935, M 26 Chadha, 2016
Cherry Mahaleb seedling Roper, 2001
Iron chlorosis Peach Adesolo, Felinem, GF
677
Jimenez et al., 2008
Root asphyxia Plum Myrobalan Amador et al., 2012
Tolerant to calcareous
soil
Peach Peach X Almond (GF
677)
Beckman & Lang
(2003)
Tolerant to salinity &
calcareous soil
Citrus Sour orange, Rangpur
lime
Cimen & Yesiloglu
(2016)
Salt tolerance Watermelon Kaijia No. 1 (C.
moschata),
Hanzhen No. 3 (L.
siceraria)
Yanyan et al., 2018
Tolerant to water
deficit
Sweet pepper (Maestral
F1)
NIBER® Mullor et al., 2020

25. 4. Improvement of stress tolerance through
protective molecules:
During abiotic stress the biosynthesis and accumulation of
different molecules thought to have protective functions in the cells is
induced. These molecules are thought to mediate their protective
function by their interaction with, or stabilizing of, different cellular
components such as membrane elements or proteins/enzymes whose
structure or function are sensitive and can be damaged as a result of
the low temperature. These are;
a) Glycine betaine (GB)
b) Heat-shock proteins (HSPs)
c) Polyamines (PAs)
d) Biostimulants
e) Thio-Urea (TU)

26. B.) Heat-shock proteins (HSPs):
These act to stabilize proteins in the cell under temperature stress
conditions by their activity as molecular chaperones. The HSPs support
protein folding, translocation, assembly, and degradation in the cells during
optimal and normal growth conditions(Kosova et al., 2007).
A.) Glycine betaine (GB):
It is an effective protectant against abiotic stress in plants including
chilling and freezing (Chen and Murata, 2008).
Plate 10: Glycine betaine synthesis and stress tolerance pathway.

27. C.) Polyamines (PAs):
Polyamines are low molecular weight aliphatic nitrogen compounds
positively charged at physiological pH. Polyamines (PAs) such as
tetramine spermine (Spm), triamine spermidine (Spd), and diamine
putrescine (Put) are considered components of plant’s defence
mechanisms against different types of abiotic stresses (Groppa and
Benavides, 2008; Alcazar et al., 2010).
D.) Biostimulants:
These are defined as products obtained from different organic or
inorganic substances and/or microorganisms, that are able to improve plant
growth, productivity and alleviate the negative effects of abiotic stresses.
(Anonymous, Franzoni G).
E.) Thio-Urea (TU):
Thio-Urea (TU), a synthetic compound containing nitrogen (as -NH2)
and sulfur (as -SH), is an important PGR, that modulates key physiological
events and mechanisms, including photosynthesis, nitrogen metabolism,
proline metabolism, antioxidant defense systems, and plant water relations
(Kaya et al., 2015; Vineeth et al., 2016)

28. Conclusion
Since abiotic stresses are significant determinants of quality and
nutritional value of fruits and vegetables during harvest, handling, storage
and distribution to consumer. There is a need to change the strategy for
addressing abiotic stress in horticulture through research, management,
capacity building and policy changes to promote innovative and rewarding
technologies.
The current mitigation and adaptation options are insufficient to face
the challenges for food security. So there is a need to more extension of
technologies like genetic engineering, transgenic approach, rootstock
breeding and protective molecules increment that will provide a potential
for genetic enhancement using desirable traits of interest in plants. Also,
there is an acute need to address various regulatory obstacles for
commercial release of various transgenic crops so that the real benefit of
this wonderful technology may reach to the consumers or the end users.

29. REFERENCES:
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Horticultural Crops. Horticulturae, 5(67): 1-2

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31. Thank you
& Have a good
day