This document discusses various plant hormones (phytohormones), including their classes, functions, biosynthesis pathways, and roles in growth and development. The major classes covered are auxins, cytokinins, gibberellins, abscisic acid, ethylene, brassinosteroids, jasmonic acid, salicylic acid, and newer identified hormones. For each class, the document describes the key hormones, their effects on processes like cell division/elongation, fruit development, stress response, and more. It also presents a case study on how salicylic acid and acetyl salicylic acid increase tolerance to heat, cold, and drought stress in bean and tomato plants.
“Plant growth regulators in relation
To Vegetable production ;Role and mode of
Action of Morphactins , antitranspirants ,
anti-auxins , Ripening retardant and Plant
Stimulants in Vegetable crop Production”
Plant hormones are naturally occurring organic substances that affect physiological processes. There are five major groups of plant hormones, such as auxins, gibberellins, cytokinins, abscisic acid and ethylene. In this presentation auxin is described with its biosynthesis, transport, pathways and physiological effects.
Plant hormones or Plant hormones are Auxin, Cytokinin, Gibberellic acid, Abscisic acid and Ethylene. they are also called as Phytohormones or Plant Growth Regulators which play key role in various stages of plant development such as seed germination, shoot formation, root formation, stem elongation, scenescence, abscision, fruit ripining etc.
“Plant growth regulators in relation
To Vegetable production ;Role and mode of
Action of Morphactins , antitranspirants ,
anti-auxins , Ripening retardant and Plant
Stimulants in Vegetable crop Production”
Plant hormones are naturally occurring organic substances that affect physiological processes. There are five major groups of plant hormones, such as auxins, gibberellins, cytokinins, abscisic acid and ethylene. In this presentation auxin is described with its biosynthesis, transport, pathways and physiological effects.
Plant hormones or Plant hormones are Auxin, Cytokinin, Gibberellic acid, Abscisic acid and Ethylene. they are also called as Phytohormones or Plant Growth Regulators which play key role in various stages of plant development such as seed germination, shoot formation, root formation, stem elongation, scenescence, abscision, fruit ripining etc.
Plant Growth Regulators
Plant Growth Promoters – They promote cell division, cell enlargement, flowering, fruiting and seed formation. Examples are auxins, gibberellins and cytokinins.
Plant Growth Inhibitors – These chemicals inhibit growth and promote dormancy and abscission in plants. An example is an abscisic acid.
Salinity stress
Categorization of salt affected soils
CAUSES OF SALINITY IN SOIL
Salinity effects on Plants
Injuries due to salt stress
different strategies to avoid salt injury
salt tolerance
salt avoidance
salt evasion
halophytes
non halophytes
glycophytes
Breeding for salt tolerance
intro-classification-salt accumulation in soil imapairs plant function and soil structure-physiological effects on crop growth and development-osmotic effect and specific ion effects-plant use different strategies to avoid salt injury
ROLE OF JASMONIC ACID IN PLANT DEVELOPMENT &DEFENCE MECHANISMBHU,Varanasi, INDIA
jasmonic acid is a plant immune hormone whicch are imortant for plant defence mechanism and development..its have important role in root growth inhibition,tuber formation,trichome formation ,senescence,flower developmentand increasing arbasculer mycorrhizal activity in root plants,recently it has been reported in various development in rice crop like spikelet development etc.....in defence its play a crucial role against insect and pathogen resistance.Recent insights into the JAs mediated plant defense cascade and better knowledge of key regulation of plant growth and development processes will help us to design future crops with increased biotic stress resistance and better adaptability under changing climate
Expains in detail the Plant Growth Hormones, Plant growth promoters and plant growth retardants/inhibitors. The role of Growth hormones in Physiological process of Plants and their application in Plant Tissue culture (Auxins, cytokinins, Gibberellins, ABA, Ethylene)
Heavy metal stress
EFFECTS OF HEAVY METAL ON PLANTS
Sources of metal toxicity
Chromium, manganese, zinc, aluminum, copper, nickel
ALLUMINIUM TOXICITY IN SOIL
Inhibition of Ca Uptake by AIuminium
Aluminium tolerance in soil by internal accumulation
Aluminium tolerance in soil by exclusion
CADMIUM TOXICITY IN SOIL
CADMIUM ACCUMULATION IN PLANTS
CADMIUM TOXICITY IN PLANTS
CADMIUM TOLERANCE MECHANISM
ROLE OF PHYTOCHELATINS
Plant Growth Regulators
Plant Growth Promoters – They promote cell division, cell enlargement, flowering, fruiting and seed formation. Examples are auxins, gibberellins and cytokinins.
Plant Growth Inhibitors – These chemicals inhibit growth and promote dormancy and abscission in plants. An example is an abscisic acid.
Salinity stress
Categorization of salt affected soils
CAUSES OF SALINITY IN SOIL
Salinity effects on Plants
Injuries due to salt stress
different strategies to avoid salt injury
salt tolerance
salt avoidance
salt evasion
halophytes
non halophytes
glycophytes
Breeding for salt tolerance
intro-classification-salt accumulation in soil imapairs plant function and soil structure-physiological effects on crop growth and development-osmotic effect and specific ion effects-plant use different strategies to avoid salt injury
ROLE OF JASMONIC ACID IN PLANT DEVELOPMENT &DEFENCE MECHANISMBHU,Varanasi, INDIA
jasmonic acid is a plant immune hormone whicch are imortant for plant defence mechanism and development..its have important role in root growth inhibition,tuber formation,trichome formation ,senescence,flower developmentand increasing arbasculer mycorrhizal activity in root plants,recently it has been reported in various development in rice crop like spikelet development etc.....in defence its play a crucial role against insect and pathogen resistance.Recent insights into the JAs mediated plant defense cascade and better knowledge of key regulation of plant growth and development processes will help us to design future crops with increased biotic stress resistance and better adaptability under changing climate
Expains in detail the Plant Growth Hormones, Plant growth promoters and plant growth retardants/inhibitors. The role of Growth hormones in Physiological process of Plants and their application in Plant Tissue culture (Auxins, cytokinins, Gibberellins, ABA, Ethylene)
Heavy metal stress
EFFECTS OF HEAVY METAL ON PLANTS
Sources of metal toxicity
Chromium, manganese, zinc, aluminum, copper, nickel
ALLUMINIUM TOXICITY IN SOIL
Inhibition of Ca Uptake by AIuminium
Aluminium tolerance in soil by internal accumulation
Aluminium tolerance in soil by exclusion
CADMIUM TOXICITY IN SOIL
CADMIUM ACCUMULATION IN PLANTS
CADMIUM TOXICITY IN PLANTS
CADMIUM TOLERANCE MECHANISM
ROLE OF PHYTOCHELATINS
Plant growth and development are intricate processes influenced by a multitude of factors, both internal and external. A thorough understanding of these processes is indispensable for students of plant biology and agriculture, especially those preparing for competitive exams like NEET and board exams. This set of comprehensive study notes aims to delve into various aspects of plant growth and development, elucidating key concepts essential for exam preparation.
For more information, visit- www.vavaclasses.com
Plant growth regulators are very important component for enhancing yield, improvement of fruit quality, abiotic stress management, ripening, etc in horticultural crops, which are briefly described in this presentation.
Role of Phytohormones in Tissue CultureApoorva Ashu
Description about phytohormones and their role in tissue culture, including descriptions about molecular basis of phytohormones with special focus on auxin and cytokinin and their role in calli development, organogenesis and somatic embryogenesis.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
2. Phytohormones or plant hormones
are chemical messengers that coordinate
cellular activities.
Major Classes of Plant Hormones
Auxins (IAA)
Cytokinins
Gibberellins (GA)
Abscisic acid (ABA)
Ethylene
8. Action of auxin:
Plant tropism
Three main guidance systems control the
orientationof plant growth:
1. Phototropism,
2. Gravitropism,
3. Thigmotropism,
12. DEVELOPMENTAL EFFECTS OF AUXIN
Auxin enhances cell elongation
Apical bud dominance
Auxin transport regulates floral bud and phyllotaxy
Auxin Promotes the Formation of Lateral and Adventitious Roots
Auxin Induces Vascular Differentiation
Auxin Delays the Onset of Leaf Abscission
Auxin Promotes Fruit Development
14. Synthetic auxins have a variety of
commercial uses
Prevention of fruit & leaf drop, induction of parthenocarpic fruit
development, thinnning of fruit & rooting of cutting for plant
propagation
If excised leaf is dipped in auxins, then rooting enhanced
Parthenocarpic fruit can be induced by treatment of unpollinated flowers
with auxins
2,4-D and dicamba are synthetic auxins which used in herbicides
2,4-D also used as weed control while monocots can inactivate synthetic
auxins rapidly than dicots.
15. Gibberellins: Regulators of Plant Height
Gibberellins are any group of plant hormones that stimulate elongation of the
stem, flowering and germination.”
Gibberellic acid was discovered by Kurosawa, a Japanese Botanist while
investigating the rice foolish seedling disease.
Gibberellins are formed in the plastids by the terpenoid pathway
and then transformed in the endoplasmic reticulum and cytosol until they reach
their biologically active form.
There are more than 70 gibberellins isolated. They are GA1, GA2, GA3 and so on.
GA3 Gibberellic acid is the most widely studied plant growth regulators.
17. Gibberellin
function
Gibberellins stimulate cell elongation and cell
division
Gibberellins enhance cell wall extensibility
without acidification
Elongation of the internodes
Gibberellins regulate the transcription of cell
cycle kinases in intercalary meristems
Accelerate seed germination
Break seed dormancy
19. Cytokinin: Regulators of Cell Division
Miller, Skoog and Strong discovered the first cytokinin in 1955.
Lentham discovered first natural cytokinin in unripe Maize grain in 1964. He called
it Zeatin .
Zeatin Is the Most abundant natural Cytokinin. Due to presence of double bond ,
zeatin has cis and trans forms. Trans forms are biologically active.
Synthesized in meristematic tissues in roots and transported to aboveground organs
A Cytokinin Receptor Related to Bacterial Two- Component Receptors Has Been
Identified . They are referred as Hybrid histidine kinase receptor protein. And their
signalling is called phosphorelay two component signalling.
Cytokinin receptors are plasma membrane bound receptors.
20.
21. Cytokinin signalling
CK receptors are like bacterial two
component histidine kinase which auto-
phosphorylating histidine kinase and are
ubiqutous signalling molecule in
bacteria.
Sensor domain is auto-phosphorylating
upon sensing the signal (CK) these
receptorphosphorylase AHP proteins.
Active AHP enters in nucleus.
It phosphorylatesARR proteins.
ARR-B protein bring about modulation
(activation) of cytokinin response
genes.
ARR-A inactivates ARR-B.
22. Cytokinin function
Cytokinins promote Movement of Nutrients
Cytokinins delay Leaf senescence
Cytokinin inhibit primary root growth:
Cytokinin promotes cell cycle
The Auxin: Cytokinin ratio regulates
Morphogenesis in cultured tissues
Cytokinins induce Bud formation in a Moss
Cytokinins modifyApical dominance and promote
lateral Bud Growth
Commercial use: it prevents pre-harvest fruit loss.
24. Ethylene: The Gaseous Hormone
It is a Growth retardant.
Ethylene as a gas, diffuses readilythroughout the plant.
Ethylene is derived from amino acid Methionine. A non-protein amino acid, 1-amino cyclopropane-l-carboxylic acid (ACC) is an
important intermediate and also immediate precursor of ethylene biosynthesis.
Ethylene can cross the cell membrane but picked up by a receptor protein creating a signal transduction pathway.
CTR1 (TWO-COMPONENT SIGNALING SYSTEM)
I. Receptors in the membrane.
II. Receptors in the ER membrane
Ethylene Signal Transduction Activates transcription of numerous enzymes.
Produced in the actively growing meristems of the plant, in senescing ripening or ageing fruits, in senescing (ageing or dying) flowers,
in germinating seeds and in certain plant tissues as a response to bending, wounding or bruising.
29. Ethylene function
Fruit ripening
Leaf Epinasty Results when ACC
from the Root Is Transported to the
Shoot
triple response
Ethylene Induces Lateral Cell
Expansion
Ethylene Enhances the Rate of Leaf
Senescence
30. Absscisic Acid: A Seed Maturation and
Antistress Signal
One of the plant hormones Called stress hormone
Transported through xylem and phloem, up and down the stem
ABA produced in leaves transported through phloem and ABA produced in roots is transported
through xylem
ABA is synthesized via the terpenoid pathway
IPP Isopentenyl pyrophosphateis a precursor for the synthesis of C40 xanthophylzeaxanthin.
Zeaxanthis is then converted to 9-cis-neoxanthin through several steps.
9-cis-neoxanthin is oxidatively cleaved to form the C15 xantoxin which is then converted to ABA
aldehyde.
ABA aldehyde is oxidized to formABA
Due to presence of doublebond,they have cis and trans forms but natural ABAare cis forms only
33. ABA Functions
ABA causes stomatal closure
ABA promotes root growth and inhibits
shoot growth at low water potentials
ABA accumulates in Dormant buds
ABA inhibits seed germination and Vivipary
ABA Promotes Leaf Senescence
34. List of phytohormones expanded to
include new chemicals
• Brassinosteroids
• Jasmonic acid
• Salicyclic acid
• Polyamines, strigolactones
• Nitric oxide
• Peptide hormones (Santner et al.2009)
35. Brassinosteroids (BRs)
Brassinosteroids are class of plant polyhydroxysteroids that recognised as new kind
of phytohormones.
The occurrenceof brassinosteroidshas been demonstrated in almost every part of plants.
About 70 BRs have been isolated from plants. (Bajguz andTretyn,2003)
At cellular level BR's can regulate
• cell elongation
• cell division
• cell differentiation.
At whole plant levels, BRs can regulate hypocotyl elongation, root and shoot development,
leaf development, male fertility, senescence, responses to biotic and abiotic stresses.
36. Jasmonic acid (JA)
Jasmonic acid is derived from fatty acid linoleic acid. It is member of jasmonate class of plant
hormones.
The major function of JA and its various metabolites is regulating plant responses to abiotic and
biotic stresses as well as plant growth and development.
Regulated plant growth and development processes include growth inhibition, senescence flower
development and leaf abscission.
JA is responsible for tuber formation in potatoes, Yams and onions.
It has an important role in response to wounding of plants and systemic acquired resistance.
Levels of Jasmonic acid rise in response to damage.
The action of Jasmonic acid induces the transcription of many genes involved in plant defense.
37. Salicyclic acid
Salicyclic acid is a monohydroxy benzoic acid, a type of phenolic acid and a betahydroxy
acid.
It is colourless crystalline organic acid.
It is widely used in organic synthesis and function as a plant hormone.
It is derived from the metabolism of salicin.
Role:
Phenolic compounds exert their influence on physiological and biochemical processes
including photosynthesis, ion uptake, membrane permeability, enzyme activities, flowering
and growth & development of plants
39. Material and method
Bean (Phaseolus vulgaris L.) and tomato (Lycopersicon esculentum L.)
Fourteen day-old plants were soil-drenched with 20 ml of distilled water or 0.05,
0.1, 0.5, 1.0 and 5.0 mM ASA or SA (dissolved in distilled water). Alternatively,
seeds were imbibed in the solutions or in distilled water for 24 h and sown in pots.
One week after soil-drenching or three weeks after the seed treatment, seedlings
were subjected to heat, cold and drought stresses.
For heat treatment, seedlings were exposed to 54 ± 0.5◦C for 3 h with an average
light intensity of 40 μMol m−2sec−1 and then returned to room temperature.
For chilling stress, plants were exposed to 0 ± 0.5 ◦ C in an incubator with an
average light intensity of 35 μMol m−2sec−1 and 16/8 h light/dark photoperiod for
two days.
Drought stress was imposed by withholding water for 7 days, then on the 8th day all
pots were watered until saturation
40.
41. Bean plants:
A) exposed to heat stress
B) pre-treated as a soil
drench with 0.5 mM ASA and
exposed to heat stress
C) exposed to chilling
D) pre-treated as a soil drench
with 0.5 mM ASA and subjected to
chilling
E) subjected to drought
F) pre-treated as a soil drench
with 0.5 mM ASA and subjected to
drought.
42. Conclusion
The physiological and biochemical basis for SA induced tolerance is not clearly at present.
The similarity of the injury mechanism between pathogenesis and stress lead us
to hypothesize that SA which induces resistance to disease also confers tolerance to the
environmental stress
Salicyclic acid and acetyl Salicyclic acid (ASA) provides multiple stress tolerance in the
plants and that salicyclic acid and its derivatives regulates the expression of stress tolerance
