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
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
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 gibberellins is described with its biosynthesis, transport and physiological effects.
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 deals with Cytokinins with its biosynthesis, transport, pathways and physiological effects.
The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA. However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway.
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
Molecular basis of plant resistance and defense responses to pathogensSenthil Natesan
In response to pathogen attack, plants have evolved sophisticated defense mechanisms to delay or arrest pathogen growth.Unlike animals, plants lack a circulating immune system recognizing microbial pathogens. Plant cells are more autonomous in their defense mechanisms and rely on the innate immune capacity of each cell and systemic signals that disseminate from infection sites (Jones and Dangl, 2006). Plant innate immunity consists of preformed physical and chemical barriers (such as leaf hairs, rigid cell walls, pre-existing antimicrobial compounds) and induced defenses. Should an invading microbe successfully breach the pre-formed barriers, it may be recognized by the plant, resulting in the activation of cellular defense responses that stop or restrict further development of the invader.
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 gibberellins is described with its biosynthesis, transport and physiological effects.
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 deals with Cytokinins with its biosynthesis, transport, pathways and physiological effects.
The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA. However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway.
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
Molecular basis of plant resistance and defense responses to pathogensSenthil Natesan
In response to pathogen attack, plants have evolved sophisticated defense mechanisms to delay or arrest pathogen growth.Unlike animals, plants lack a circulating immune system recognizing microbial pathogens. Plant cells are more autonomous in their defense mechanisms and rely on the innate immune capacity of each cell and systemic signals that disseminate from infection sites (Jones and Dangl, 2006). Plant innate immunity consists of preformed physical and chemical barriers (such as leaf hairs, rigid cell walls, pre-existing antimicrobial compounds) and induced defenses. Should an invading microbe successfully breach the pre-formed barriers, it may be recognized by the plant, resulting in the activation of cellular defense responses that stop or restrict further development of the invader.
Feed concentration and feed flow rate along with the relative durations of the mist-ON/ mist-OFF cycles are the important process parameters for the growth of hairy roots in a nutrient mist reactor. The paper presents guidelines for choosing these parameters for an efficient operation of the reactor with intermittent mist-ON/mist-OFF cycles. It is based on a theoretical model of nutrient mist reactor at the root bed level and its numerical simulation. This model describes the evolution of liquid holdup and concentration present in the root bed. One can also run the reactor with intermittent mist-ON and mist-OF cycles, at very low cumulative mist-ON duration for any given total run time to prevent any nutrient deficiency and water logging in the bed. It is found that in some conditions mist has to be switched on for only about 10% of the total runtime while the mist can be switched off for 90% of the total run time. The duration of both mist-ON / mist-OFF cycles are effected by the process parameters and thus, the ratio of mist-ON time to total run time, may not follow any fixed trend in some cases. The guidelines presented here will help in efficient operation and design of nutrient mist reactors.
Root genetic research and its application in plant breeding or crop improvementOm Prakash Patidar
UNIVERSITY OF AGRICULTURAL SCIENCES, DHARWAD
DEPARTMENT OF GENETICS AND PLANT BREEDING Master’s seminar-II
Root genetic research and its applications in plant breeding
Speaker: Om Prakash Patidar Date: 20/03/2015 ID No.: PGS13AGR6140 Time: 3:00 PM
Synopsis
Roots play an essential role in the acquisition of water and minerals from soils. Root system architecture (RSA), the spatial configuration of a root system in the soil, is used to describe the shape and structure of root system. Its importance in plant productivity lies in the fact that major soil resources are heterogeneously distributed in the soil, so that the spatial deployment of roots will substantially determine the ability of a plant to secure edaphic resources. Measuring crop root architecture and assaying for changes in function can be challenging, but examples have emerged showing that modifications to roots result in higher yield and increased stress tolerance.1
A marker-assisted back-crossing (MABC) breeding programme was conducted to improve the root morphological traits, and thereby drought tolerance, of the Indian upland rice variety, Kalinga III. The donor parent was Azucena, an upland japonica variety from Philippines. Five segments on different chromosomes were targeted for introgression; four segments carried QTLs for improved root morphological traits and the fifth carried a recessive QTL for aroma. It significantly increased root length under both irrigated and drought stress treatments.2
Alteration of root system architecture improves drought avoidance through the cloning and characterization of DEEPER ROOTING 1 (DRO1), a rice quantitative trait locus controlling root growth angle. Higher expression of DRO1 increases the root growth angle, whereby roots grow in a more downward direction. Introducing DRO1 into a shallow-rooting rice cultivar by backcrossing enabled the resulting line to avoid drought by increasing deep rooting, which maintained high yield performance under drought conditions relative to the recipient cultivar.3
GmEXPB2, A vegetative -expansin gene, clone from a Pi starvation-induced soybean cDNA library. GmEXPB2 was found to be primarily expressed in roots, and was highly induced by Pi starvation, and the induction pattern was confirmed by GUS staining in transgenic soybean hairy roots. Results from intact soybean composite showed that GmEXPB2 is involved in hairy root elongation, and subsequently affects plant growth and P uptake, especially at low P levels.4
Candidate Aluminum tolerance proteins include organic acid efflux transporters, with the organic acids forming non-toxic complexes with rhizosphere aluminum. ge
— The diseases caused by bipartite Begomoviruses have emerged as overwhelming problem in various cropping systems of Pakistan. The study was conducted to evaluate the potential of induced resistance in mungbean to Mungbean yellow mosaic virus (MYMV) disease. In this work, resistance to MYMV infection was induced in mungbean plants by activating the Salicylic acid (SA) pathway using SA and Benzothiadiazole (BTH) as treatments. The resistance was characterized by evaluating symptom appearance and virus titter through ELISA. Elicitors i.e., SA and BTH were applied at different concentrations to enhance the innate resistance of mungbean by the induction of defense related compounds. All treatments were helpful in reducing plant infection but the most effective treatment was the combination of SA@5mM and BTH@150mg/L as compared to virus inoculated control. Three weeks analysis showed peak accumulation of defense related enzymatic antioxidants and phenols in the mungbean leaves treated with SA and BTH. Higher enzymatic activity was observed in elicitor treated plants followed by inoculation with MYMV. As the resistance increased due to the application of SA & BTH the enzymatic activities of SOD, POD, and CAT were also increased during second week after application of elicitors. This study revealed that SA and BTH are potential source for management of MYMV by enhancing the level of protection through induction of systemic acquired resistance.
Carbohydrates in plant immunity By Kainat RamzanKainatRamzan3
The main classes of carbohydrates associated with plant immunity, their role, and mode of action. More precisely, the state of the art about the perception of “PAMP, MAMP, and DAMP
(Pathogen-, Microbe-, Damage-Associated Molecular Patterns) type” oligosaccharides is
presented and examples of induced defense events are provided.
As a most notable member in the stilbenoid family, resveratrol (3,5,4′-trihydroxy-trans-stilbene) has a wide range of biological activities which may have the impact on human health, including antioxidant, anti-inflammatory, cardioprotective, antiviral, anticancer, and antiaging properties as demonstrated in in vitro and animal studies.
The concentration of this amino acid is higher in tomato compared with many vegetables such as carrots, onions or pepper. In addition, glutamate provides the characteristic ‘‘umami taste’’ to foods with high free glutamate content such as cheese, tomato and mushrooms, which are major ingredients in cooking.
Disease Resistance in plants : Detailed insights on Plant- Pathogen Interactionaishnasrivastava
Plant Immune responses that can be divided into three essential steps:
microbial recognition by immune receptors, signal transduction
within plant cells, and immune execution directly suppressing
pathogens.
Microbiota-mediated pathogen suppression
Nutrient,water and pH-mediated pathogen suppression
Molecule -mediated pathogen suppression
Physical barrier-mediated pathogen suppression
Non - Host Resistance
Genetic Intervensions
Biochemical Resistance Mechanism
Role of antimicrobial peptides in plant disease management N.H. Shankar Reddy
It is one of the advanced topics in plant disease management, detailed information about antimicrobial peptides and their role in plant disease management is furnished clearly.
Growth Pattern, Molecular Identification and Bio molecules Analysis of FOMITO...journal ijrtem
Abstract : Fomitopsis feei, a brown rot fungus is identified tentatively using morphological characteristics and confirmed phylogenetically by 28S rDNA analysis and sequence was submitted in EMBL Nucleotide Sequence Database. Its growth pattern was studied on eight different solid media and found to be good on Malt extract agar medium. Biomolecules such as proteins and lipid were screened qualitatively and estimated quantitatively. Aminoacid analysis by chromatography and fatty acid analysis by FAME were also done and revealed that tryptophan (20.53%), valine (20.51%) and cis-linoleic acid (43.38%) and palmetic acid (17.88%) were in high percentage.
Key words : Fomitopsis feei, growth, molecular identification and biomolecules
Carotenoids, also called tetraterpenoids, are organic pigments that are produced by plants and algae, as well as several bacteria and fungi. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms.
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.
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.
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.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Comparative structure of adrenal gland in vertebrates
Action and Biosynthesis of Jasmonic Acid
1.
2.
3. Plants have evolved chemical defense strategies to protect
themselves upon wounding are:-
(a) formation of proteineous defense compounds-Proteinase
Inhibitors (PINs)
(b) formation of toxic compounds -Nicotine
(c) emission of volatiles which attract insect parasitoid and
predators- Allyl Isothiocynate
Jasmonic acid (JA) occurs as an essential signaling compound.
Jasmonic acid methyl ester (JAME) shown to induce PINs in
plants.
5. Peptide -Systemin
Lipid-derived- Jasmonic acid (JA)
As essential signals in wound-induced gene expression
It cover following aspects:
(a) Systemin signaling,
(b) JA biosynthesis and action,
(c) Orchestration of various signals such as JA, H2O2 etc.
(d) Local and systemic response,
(e) Amplification in wound signaling.
6. Plant peptide hormone.
First plant hormone that was proven to be a peptide isolated
from tomato leaves (Clarence A. Ryan, 1991)
Hydroxyproline-rich glycopeptides in tobacco in 2001.
AtPEPs (Arabidopsis thaliana Plant Elicitor Peptides) were
found in Arabidopsis thaliana in 2006.
It plays a critical role in defense signaling in plants
It promotes the synthesis of over 20 defense-related proteins
(a) Antinutritional proteins-proteases
(b)Signaling pathway proteins
Gene of transgenic tobacco plants expressing SR160 responded
clearly to systemin
7. Over-expression of prosystemin (tobacco and tomato)-
significantly decrease damage caused by Manduca sexta
Continuous activation of prosystemin
- affecting the growth,
-physiology and reproductive success of plants
When systemin silence, production of protease inhibitors in
tomato severely impaired and larvae feeding on the plants
grow three times as fast
It increases the production of jasmonic acid
It induces the production of protease inhibitors
It affect plants' responses to salt stress and UV radiation
10. Jasmonate and its derivatives are lipid-based hormone
signals.
Regulate a wide range of processes in plants;
-growth
-photosynthesis
-reproductive development
JAs are critical for
-plant defense against herbivory
-plant responses to poor environmental conditions
As volatile organic compounds
11. Initial discovery of methyl jasmonate (MeJA) as a secondary
metabolite in essential oils of jasmine.
Role in plant defense was first shown by Farmer and Ryan
(1990) who demonstrated the induction of proteinase
inhibitors by MeJA and JA as part of the defense response
against herbivorous insects.
Jasmonic acid oxygenated fatty acidsoctadecanoid
pathway
Pentacyclic ring structure
Dgl gene is responsible for maintaining levels of JA in Zea
mays.
12. Function of jasmonic acid include :-
as signaling molecules :-
- plant development
-adaptation to environmental stress
-involved in plant defense reactions
-activates the expression of protease inhibitor
as hormone :-
-senescence
-tendril coiling
-flower development
-leaf abscission
-trichome induction- Tomato
- mechanotransduction- Bryonia
- tuberization- Potato
13. JA biosynthesis pathway was elucidated by Vick and
Zimmerman
JA synthesized from linolenic acid
First oxygenated by lipoxygenase (LOX), yield 13(S)-
hydroperoxy linolenic acid (13HPOT)
Apparent hydroperoxide cyclase activity was found to be
present in many plant species
OPDA is further metabolized to JA
It include -Reduction of the cyclopentenone ring of OPDA to
yield the respective cyclopentanone.
14. Precursor for JA biosynthesis is linolenic acid
LA is present in cellular lipids where it originates from
esterified oleic acid, which is successively converted to
linoleic acid
Early steps of JA biosynthesis are catalyzed by the chloroplast
enzymes :-
LOX
AOS
AOC
16. JA and JAME are lipid-derived signals.
They are synthesized by the octadecanoid pathway, where 12-
oxophytodienoic acid (OPDA) is a central intermediate.
The initial reaction is the 13-lipoxygenase (13-LOX)-catalyzed
insertion of molecular oxygen into position 13 of a-linolenic
acid (a-LeA) most likely released from plastid envelope
membrane.
Then (13-S)-hydroperoxy linolenic acid (13-HPOT) is
converted by an allene oxide synthase (AOS) specific for 13-
HPOT into an unstable allene oxide that is further processed
by allene oxide cyclase (AOC).
17. Three possible routes leading to JA :-
LA is liberated by an acylhydrolase or a
phospholipase for subsequent oxygenation by a 13-
LOX.
Lipase cleaves 13-HPOT generated by a membrane-
associated LOX acting on esterified.
Lipid-bound 13- HPOT is further metabolized by
AOS and AOC to yield JA.
Contd….
20. JA may be metabolized by:-
(a) methylation at the carboxylic acid group
(b) decarboxylation to cis-jasmone,
(c) conjugation to amino acids or the ethylene precursor 1-
aminocyclopropane-1-carboxylic acid (ACC)
(d) hydroxylation of the pentenyl side chain to 11-OH-JA or 12-
OH-JA
(e) glucosylation at the carboxylic acid group or the 12-OH-
group
(f) reduction of the keto group of the pentanone ring leading
to cucurbic acids
23. JA is a secondary metabolite synthesized and secreted in the
late growth phase or the stationary phase after 5-10 days
fermentation.
Botryodiplodia theobromae , mutants of Gibberella fujikuroi ,
Collihya conffuens , Coprinus alkalinus and Mvcena
tintinabulum have been reported as JA producers.
Species of the genus Botryodiplodia are able to grow in
minimum defined media . JA production by B. theobromae
increased with sucrose and glucose as carbon source.
JA production by Lasiodiplodia theobromae is similar when
organic or inorganic nitrogen sources are use.
24. Jasmonic acid is also converted to a variety of derivatives
including esters such as methyl jasmonate; it may also be
conjugated to amino acids.
According to an October 2008 BBC News report,
Researchers at the UK's Lancaster University have signed a
licensing deal with an American company (Plant
Bioscience Limited) to market jasmonic acid as a seed
treatment .(EU Regulation)
The company has rolled out the technology progressively,
starting with soybean and peanut in the USA in 2010, and
product sales have increased year on year
Field application of JA may enhance the efficacy of
parasitoids and predators as biological control agents.
25. JA seed treatment stimulates the natural anti-pest defenses of
the plants that germinate from the treated seeds, without
harming plant growth.
Exogenous application of JA on rice plants elicits the production
of proteinase inhibitors, phytoalexins, PRs, and salt-induced
proteins (Tamogamia et al., 1997; Rakwal and Komatsu, 2000;
Rakwal et al., 2001; Kim et al., 2003) and it may increase the
emission of volatiles.
JA application to rice plants on the host-searching behavior of
the rice brown planthopper Nilaparvata lugens and its
mymarid egg parasitoid Anagrus nilaparvatae
Exogenous application of MeJA increases the release of volatile
organic compounds (Halitschke et al., 2000), which enhances
the mortality rates of the herbivores by attracting the natural
enemies of herbivores (Kessler and Baldwin 2001)
26. Insight gained from these studies should lead to better
design of durable plant defense and improved utilization
of proteins and genes from non plant sources for plant
protection
Elucidation of the regulatory functions of JA on plant
growth and development, and on the responses to
environmental stress, will require the characterization of
components and mechanisms involved in its synthesis,
perception and transduction pathways.
Editor's Notes
Plants have evolved chemical defense strategies to protect themselves upon wounding are:-
(i) formation of proteineous defense compounds such as proteinase inhibitors (PINs), which affect nutrient consumption by the herbivores
(ii) formation of toxic compounds such as nicotine
(iii) emission of volatiles which attract insect predators
In all these responses of wounded plants jasmonic acid (JA) occurs as an essential signaling compound.
Jasmonic acid methyl ester (JAME) shown to induce PINs in plants, thereby attributing to an ‘‘immunization’’ against herbivore attack
Transcription factors involved in signalling pathways of JA and
cross-talk to ethylene and SAGibberellin and Jasmonic Acid Have a Synergistic
Effect on Trichome Induction
Among transcription
factors acting downstream of JA in stress responses are
the ethylene response factor 1 (ERF1), the bHLHzip-type
transcription factor ATMYC2 (Lorenzo et al., 2004),
WRKY70 and the newly found family of ORAs (identified
by J. Memelink’s group). ORAs are the Arabidospis homologs
of ORCAs initially identified in Catharanthus roseus
cell suspension cultures (Memelink et al., 2001). Among
them, ORA47 is a COI1-dependent positive regulator of
JA biosynthesis, whereas ORA59, ERF1, ORA37, MYC2
and WRKY70 act positively or negatively on different
groups of defence genes (Fig. 6). The antagonistic action
of MYC2 and ERF1 may cause the independence
between wound signalling and pathogen
The wound response of tomato leaves, wound-induced formation of PINs
systemin as a specific inducer of PIN
Systemin is a plant peptide hormone involved in the wound response in the Solanaceae family. It was the first plant hormone that was proven to be a peptide having been isolated from tomato leaves in 1991 by a group lead by Clarence A. Ryan. Since then other peptides, with similar functions have been identified in tomato and outside of the Solanaceae. Hydroxyproline-rich glycopeptides were found in tobacco in 2001 and AtPEPs (Arabidopsis thaliana Plant Elicitor Peptides) were found in Arabidopsis thaliana in 2006
It induces the production of protease inhibitors which protect against insect herbivores, other peptides activate defensins and modify root growth.
The main function of systemins is to coordinate defensive responses against insect herbivores but they also affect plant development
Systemin plays a critical role in defence signalling in tomato
It promotes the synthesis of over 20 defence-related proteins, mainly antinutritional proteins, signaling pathway proteins and proteases.[15] The over-expression of the prosystemin resulted in a significant decrease of the larvae damage, indicating that a high level of constitutive protection is superior to an inducible defence mechanism.[25] However, the continuous activation of prosystemin is costly, affecting the growth, the physiology and the reproductive success of tomato plants.[26] When systemin was silenced, production of protease inhibitors in tomato was severely impaired and larvae feeding on the plants grew three times as fast
Systemin activates processes which help tomato deter insect herbivores, such as this hornworm Manduca sexta
(cell-type-specific occurrenceAOC,AOS and LOX) ). In tomato, wounding of a single leaf can result in the
induction of proteinase inhibitors throughout the aerial portion
of the plant
Jasmonate (JA) and its derivatives are lipid-based hormone signals that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herbivory and plant responses to poor environmental conditions and other kinds of abiotic and biotic challenges. Some JAs can also be released as volatile organic compounds (VOCs) to permit communication between plants in anticipation of mutual dangers.[2]
The isolation of methyl jasmonate from jasmine oil derived from Jasminum grandiflorum led to the discovery of the molecular structure of jasmonates and their name.[3]
Isolation of methyl jasmonate from jasmine oil derived from Jasminum grandiflorum led to the discovery of the molecular structure of jasmonates and their name.It is a member of the jasmonate class of plant hormones.
Jasmonic acid (JA) is derived from the fatty acid linolenic acid. It is a member of the jasmonate class of plant hormones. It is biosynthesized from linolenic acid by the octadecanoid pathway.
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.[1] Regulated plant growth and development processes include growth inhibition, senescence, tendril coiling, flower development and leaf abscission. JA is also responsible for tuber formation in potatoes and yams. It has an important role in response to wounding of plants and systemic acquired resistance. The Dgl gene is responsible for maintaining levels of JA during usual conditions in Zea mays as well as the preliminary release of jasmonic acid shortly after being fed upon.[2] When plants are attacked by insects, they respond by releasing JA, which activates the expression of protease inhibitors, among many other anti-herbivore defense compounds. These protease inhibitors prevent proteolytic activity of the insects' digestive proteases or "salivary proteins",[3] thereby stopping them from acquiring the needed nitrogen in the protein for their own growth
Salicylic Acid Inhibits Plant Response to Jasmonic Acid Jasmonic Acid Increases Trichome Density and Number jasmonates as a genuine class of plant hormones throughout the plant kingdomThe initial discovery of methyl jasmonate (MeJA) as a secondary metabolite in essential oils of jasmin .
A role in plant defense was first shown by Farmer and Ryan in 1962 who demonstrated the induction of proteinase inhibitors by MeJA and JA as part of the defense response against herbivorous insects
Jasmonates oxygenated fatty acidsoctadecanoid pathway
Pentacyclic ring structure
Jasmonates are derived from oxygenated fatty acids via the octadecanoid pathway,they have regulatory function as signalingmolecules in plant development and adaptation to environmental stress
TABLE 1. Band may act as a resistance mechanism of wheat against insect herbivores.
Jasmonates in development
Developmental
process
Putative
signal
Alteration/
species
Root growth JA, JA-Ile Inhibition
Seed germination JA Inhibition
Tuber formation 12-OH-JA Induction/
potato
Tendril coiling OPDA Stimulation/
Bryonia
Nyctinasty 12-OH-JA
Glu Stimulation/ Trichome Formation JA Induction/ Tomato Senescence JA Stimulation Flower Development Anther development þ Dehiscence JA Induction/ Arabidopsis Female organ Development JA Induction/Tomato Filament Elongation JA Induction/Arabidopsis Jasmonate Biosynthesis and ActionProtease inhibitors prevent proteolytic activity of the insects' digestive proteases or "salivary proteins”thereby stopping them from acquiring the needed nitrogen in the protein for their own growth
Jasmonic acid synthesized from linolenic acid,which is first oxygenated by lipoxygenase to yield 13(s)hydroperoxy linolenic acid(13HPOT),action of two consecutive
Metabolism includes :-
Reduction of the cyclopentenone ring of OPDA to yield the respective cyclopentanone (OPC 8:0)
Followed by three cycles of b-oxidation
> shortening of the octanoic acid side chain
>formation of JA
e enzymes namely,allene oxide synthatase and AO cyclase
Precursor for JA biosynthesis is linolenic acid
LA is present in cellular lipids where it originates from esterified oleic acid, which is successively converted to linoleic acid
Early steps of JA biosynthesis are catalyzed by the chloroplast enzymes LOX, AOS, and AOC
Figure 3. Overview of jasmonate biosynthesis and metabolism. JA biosynthesis and metabolism involve three compartments in the cell; that is, the chloroplast where OPDA and dnOPDA are synthesized, the peroxisome where (dn)OPDA is converted to JA, and the cytosol where further modifications of JA take place. Text and arrows in solid colors are supported by experimental evidence ,hypothetical routes are depicted in lighter tones many of which involve membrane-localized esterified substrates. Transport of the various metabolites between compartments is indicated by dotted arrows and is hypothetical. For clarity of the figure, steps beyond 13-hydroperoxy linoleic acid were omitted but would lead to 9,10- dihydro-JA. Abbreviations are given in the text
Figure 5. Cell-type specific location of enzymes of JA biosynthesis in vascular bundles of tomato leaves. LOX,AOS and AOC proteins are located in companion cells (CC) and sieve elements (SE) of the vascular bundles as indicated by immunocytochemical detection with specific antibodies (right pictures, the sieve plate is indicated by an asterisk). As shown by in situ hybridization (lower picture) AOC mRNA accumulates exclusively in companion cells, but not in the triangle-shaped sieve elements suggesting AOC protein transport via plasmodesmata
FIG. 2. Intracellular location of enzymes and intermediates in JA biosynthesis, illustrated on a SEM of a barley mesophyll cell showing the associated cellular compartments
Fig 4The carboxylic acid side-chain can be conjugated to the ethylene precursor 1-amino cyclopropane-1-carboxylic
acid (ACC), methylated by JA methyl transferase (JMT), decarboxylated to cis-jasmone, conjugated to amino acids such as Ile by JA amino acid synthase
(Arabidopsis, JAR1; tobacco, JAR4) or glucosylated. The pentenyl side-chain can be hydroxylated in positions C-11 or C-12. In the case of 12-OH-JA,
glucosylation or sulfation are subsequent reactions. Reduction of the keto group of the pentenone ring can lead to cucurbic acid
Figure 4. Amplification in wound signaling of tomato. Wounding leads to prosystemin expression in parenchymatic cells of vascular bundles. Systemin processed from prosystemin can activate AOC expression which occurs in vascular bundles and the surrounding parenchymatic cells. Consequently, JA is generated preferentially in vascular bundles and may activate PROSYSTEMIN expression. This amplification in the vascular tissue is compromised in AOC sense plants and is blocked in AOC antisense plants as indicated by the immunocytochemical detection of AOC
However, know- ledge about JA production by microorganisms is still limited
The commercial standing of the JA seed treatment was enhanced by the grant of a USA patent in 2012.
This chemical have a role in pest control, according to an October 2008 BBC News report. Researchers at the UK's Lancaster University have signed a licensing deal with an American company to market jasmonic acid as a seed treatment.
Research on this topic has solidified our understanding of the chemistry and
biosynthetic pathway of jasmonates. However, additional research is needed
into the mechanisms that regulate the synthesis of JA in plants during development
and in response to wounding and oligosaccharides and peptides that
modulate JA biosynthesis, Although
the biochemistry and molecular biology of JA
synthesis is the subject of intensive work, our knowledge
of this biosynthetic pathway lacks information on
subcellular compartmentalisation of some of the steps
involved and cell type specificity of the pathway.