PGR513_Jasmonic Acid as a plant growth and hormones
- 1. HORT 513. Plant Growth Regulators Dr. M. Jahedur Rahman Professor Department of Horticulture Sher-e-Bangla Agricultural University
- 2. Syllabus: 1. Cytokinin 2. Ethylene 3. ABA 4. Jasmonic acid 5. Salicylic acid 6. Application of PGR in agriculture
- 3. Marks Distribution: Item No. Marks Date Instructor Quiz 3 10 Sep., Oct. & Nov. MN Islam MJ Rahman Mid Term 2 40 Oct. & Nov. MN Islam MJ Rahman Assignment 1 10 Sep. – Nov. MN Islam MJ Rahman Final 1 40 December?? MN Islam MJ Rahman Total: 100
- 4. JASMONIC ACID & ITS ROLE IN PLANTS
- 5. Introduction Growth “Irreversible change in mass, i.e. increase in size, volume and weight of any part of plant’s body” It means quantitative increase in body. Cell division, Cell enlargement. Development “Irreversible change in state” It means thequalitative change in plant body. Seed, Seedling, Vegetative, maturation, Flowering. Development is phase to phase process.
- 6. Plant’s growth and development are under the control of two sets of internal factors. Chemical messengers Proper utilization of these raw materials is under the control of certain “chemical messengers” which can be classified into hormones and vitamins. Introduction Nutrients Nutritional factors such as the supply of carbohydrates, proteins, fats and others constitute the raw materials required for growth. ► Nutrients ► Chemical messengers
- 7. The site of synthesis is different from the site of action. Plant hormones are physiologically active. Vitami n Vitamins are used in the same part without being transported Vitamins by themselves are physiologically inactive. They act as co-factor of enzyme. Introduction The term Hormone is derived from a Greek root ‘hormao’ which means ‘to stimulate’ ( Beylis and Starling, 1902). Thimann (1948) suggested using the term ‘Phytohormone’ for Hormones of plant. Hormone
- 8. Phytohormones are organic substances produced Naturally by theplants which in minute/low concentration increase, Decrease, modify the growth and development. 1) Plant growth hormones 2) Plant growth promoting substances 3) Plant growth regulators Phytohormones Other names
- 9. synthetic substances influence Plant Growth regulators (PGR) refers to natural or the growth and development. • All plant hormone are plant growth regulators but, • All plant growth regulator are not plant hormones Plant Growth Regulators
- 10. 1. Natural hormone Produced by some tissues in the plant. Also called Endogenous hormones. e.g. IAA. 2. Synthetic hormone Produced artificially and similarto natural hormone in physiological activity. Also called Exogenous hormones. e.g. 2,4- D, NAA etc. 3. Postulated hormone Also produced spontaneously in theplant body, buttheir structure and function is not discovered clearly. e.g. Florigen, Vernalin. Classification of PGR’s On the Basis of Origin
- 11. Growth promotors (Increase growth of plants): Auxins Gibberellins Cytokinins Classification of PGR’s Stress and other hormones: Jasmonates Salicilic acids, etc On the Basis of Nature of Function Growth Inhibitors (Retard growth of plants) ABA Ethylene
- 12. Salicylic acid Abscisic acid Jasmonates Brassinosteroids Ethylene Cytokinins Gibberellins Auxins Plant hormones
- 13. JASMONIC ACID First isolated in culture filtrate of fungi Lasiodiplodia theobromae. Aldridge et. al.,(1971).J.Chem.Soc.Chem. Comm. 1623- Jasmonates are cyclopentanone compound or plant hormones derived from α-linolenic acid. It includes group of oxygenated fatty acids collectively called oxylipins and Jasmonic Acid is a precursor to different compounds to this group. Methyl jasmonate was first isolated from the essential oil of Jasminum grandiflorum Demole et. al.,(1962).Helv. Chim.Acta.45:675-695 They are ubiquitous in plant kingdom and are also produced by certain fungi.
- 14. A E A. Structural formula: Jasmonic acid (JA) A. Chemical Formula: C12H18O3 B. Molar Mass: 210.27 g/mol C. Boiling point: 160 °C D. Density: 1.1 g/cm³ E. Jasmin plant: Jasminum grandiflorum
- 15. BIOSYNTHESIS OF JASMONATES Jasmonic acid synthesized from fatty acid(α- linolenic acid) Lipoxygenase (LOX), AOS (Allene oxide synthase), AOC (Allene Oxide Cyclase) are key enzymes of JA biosynthesis in Chloroplast, and they form OPDA (oxo-phytodienoic acid). OPDA is transported to peroxisome through ABC transporter COMATOSE (CTS) Reduction of cyclopentanone ring of OPDA is catalyzed by peroxisomal OPR enzyme Three cycles of β-oxidation occurs to give finally Jasmonic Acid. Enzymes involved are: • • • ACX1 (Acyl-CoA oxidase in tomato) MFP (Multifunctional Protein) KAT (L-3-ketoacyl CoA thiolase) The JA and its metabolic derivatives are collectively called JASMONATES Fig : Biosynthetic Pathway of Jasmonic Acid CTS Source: Wasternack et .al.,(2002).PNARMB.72:165-221
- 16. Derivatives of Jasmonic acid – THE JASMONATES Carboxylic conjugated acid side chain to ACC(1- amino cyclopropane-1-carboxylic acid) Methylatedform by JA methyltransferase Decarboxylated to cis-jasmone Conjugated to AA such as Ile by JA amino acid synthase (JA- IIe - Jasmonic Acid-Isoleucine) Reduction of keto group of pentanone ring to cucurbic acid side in position chain C- 11 Pentenyl hydroxylated and C-12 Fig : Different Metabolites Produced from Jasmonic Acid Jasmonic Acid-Isoleucine
- 17. S. No Process Putative Signals Alteration/Species 1 Root Growth JA,JA-Ile Inhibition 2 Seed Germination JA Inhibition 3 Tuber Formation JA-OH,JA Induction/Potato 4 Tendril Coiling OPDA Stimulation/Bryonia 5 Nyctinasty JA Stimulation/Albizzia 6 Trichome formation JA Induction/Tomato 7 Senescence JA Stimulation 8 Flower Development Anther Development and dehiscence Female Organ Development Filament elongation JA Induction/Arabidopsis Induction/Tomato Induction/Arabidopsis 12 Biotic Stress JA, JME,OPDA Resistance/Ubiqutitous DIFFERENT PHYSIOLOGICAL ROLES OF JA Source: Wasternack, C. (2007).Annals of Botany.100:681- 697
- 18. STRESS AND ITS TYPES STRESS BIOTIC ABIOTIC Fungi Bacteria Virus Nematodes Light Pesticide Heavy metal Drought Salinity Temperature Herbivores Stress is any change in the environmental condition that may adversely affect the plant’s growth, development and adaptability
- 19. Biotic stress perception Stress signaling Virus Nematodes Wounding by herbivores Insect attack Fungal pathogen Bacteria Jasmonates ? Downstream activation of stress related/resistance genes
- 20. ROLE OF JA IN RESISTANCE 1. Increased endogenous level of JA on treatment of Arabidopsis with necrotrophic fungus A. brassicola. Penninckx et al.(1996). Plant Cell.8:2309-2323 2. Biosynthetic necrotrophic and SignalingArabidopsis mutants were to attack more sensitive fungal pathogen Phytium by mutants and necrotrophic bacteria Erwinia carotovora (jar1,coi1) and fad3-2fad7-1fad8 (coi1 mutants). Staswick et al., (1998).Plant Journal 15:747-754; Vijayan et al.,(1998).PNAS USA 95:7209-7214 3. Transgenic plants overexpressing JMT (jasmonic acid carboxyl methyltransferase) and thus higher levels of methyl jasmonate more resistant to necrotrophic pathogen Botrytis cinera. Walling (2000 ). Journal of Plant Growth Regulators 19: 195-216 4. The fad3-2fad7-1fad8 mutant more sensitive to attack by fungus Bradysia and coi1 is more sensitive to Diamond –back moth. McConn et al.,(1997). PNAS USA.94:5473-5477; Xie et al (1998). Science 280: 1091-1094 Source: Berger,(2002).Planta 214:497-504
- 21. Mutant Biochemical Significance Role of Mutant Expression of JA responsive genes Effects coi Coronatine insensitive JA Signaling Reduced Sensitivity to insect and necrotrophic pathogens increased fad Defective Fatty Acid Desaturase JA Biosynthetic Reduced Sensitivity to insect and necrotrophic pathogens increased cev Constitutive Expression of VSP JA Signaling Increased Increased sensitivity to biographic pathogens jar JA Resistant JA Signaling Reduced Increased sensitivity to necrotrophic pathogens opr Defective OPDA Reductase JA Biosynthetic Reduced Increased sensitivity to insects jin JA Insensitive JA Signaling Reduced Increased sensitivity to pathogens Some mutants of JA and Resistance in plants
- 22. Source:Farmer and Ryan(1992).The Plant Cell.4:129-134 Mechanism of action of JAs in biotic stress Source:Wasternack (2007).Annals of Botany.100:681-697
- 23. OVERALL MECHANISM OF SYSTEMIC RESPONSE Wounded leaves produce an 18-amino acid peptide called systemin from carboxyl terminal of prosystemin (200 AA precursor) in PP and it elicits production of JA in companion cell-sieve element complex. JA moves throughout the plant in the phloem. Covalently modified JA (JA-x) play important role in systemic signaling. signal is recognized at the target cell e.g. mesophyll (leaf) Jasmonic acid turns on defense related genes (genes for proteinase inhibitor etc.) in target cells. Source: Schilmiller and Howe (2005). Current Opinion in Plant Biology . 8:369-
- 25. Fig: Amplification of wound signaling of tomato Wounding Systemin AOC OPDA/JA Systemin Prosystemin Prosystemin Amplification of wound signaling is a major event in systemic defense Systemin activates AOC which in turn activates Prosystemin through OPDA/JA. OPDA/JA again activates back the AOC. In systemic response once JA is synthesized, its cyclic production of JA can occur by positive feedback mechanism JA is a systemic signal that leads to systemic expression of genes encoding Proteinase inhibitors(PINs) The plant may develop some resistance against subsequent herbivore attack. Thus JA signaling is necessary in systemic response in leaf. AMPLIFICATION OF SYSTEMIN SIGNAL Source:Wasternack et al(2006).163: 297-
- 26. SYSTEMIC RESISTANCE AND ROLE OF JAs Initial infection result in formation of necrotic lesions SA concentrations increase and methyl-SA is released in distal plant tissue PR proteins in the non-invaded parts of the plants are synthesised resulting in reduction in disease symptoms after subsequent infection of many pathogenic species. Source:Harman et. al.(2004) .Nature Reviews Microbiology. 2:43-56 SAR: Systemic resistance in plants Systemic Acquired Resistance (SAR) Induced Systemic Resistance (ISR) ISR: Non pathogenic root colonizing rhizobacteria e.g. P. fluorescens or wounding initiates ISR ISR does not depend on SA and PR protein ISR requires both JA and ethylene signalling Systemin is involved in ISR which is absent in SAR.
- 27. TRANSCRIPTIONAL REGULATION OF JA Fig: Transcription factors involved in signalling pathways of JA Source: Wasternack(2007). Annals of Botany100:681-697 Four major of interacting players of: 1.a JA signal 2.the SCF-type E3 ubiquitin ligase SCFCOI1 3.Jasmonate ZIM-domain (JAZ) repressor proteins that are targeted by SCFCOI1 for degradation by the ubiquitin/26S proteasome pathway ,and 4.transcription factors (TFs) Howe et. al.(2008)Current Opinion in Plant Biology 11:428-235 Transcriptional regulation mechanism: 1.Expression of regulatory TFs for JAs 2.Cross talk with the TFs responsible for expression of other hormones.
- 28. Cross Talk with Ethylene and JA •The antagonistic action of MYC2 and ERF1 may cause independence between wound signaling and pathogen defence signaling Lorenzo et al (2004)Plant Cell 16:1938-1950) •JA alone induce the expression of AtMYC2 responsible for the activation of wound response genes and for the repression of pathogen response genes. signals through the induction •The cooperation of ET and JA of ERF1 leads activation of PR genes and to the repression of WR genes •Therefore, the interplay between ERF1 and AtMYC2 allows the plant selection of the correct set of genes in response to these two stresses Schematic Representation in response to Pathogens and Wounding Source: Wasternack(2007). Annals of Botany100:681-697
- 33. Why we study JAs? / Relevance of JAs studies Plant lack an immune system like in animals but posses mechanism that recognizes potential pathogens and initiate defense responses. During their biochemical evolution, the plants are devised with certain magic molecules of defense (secondary metabolites) like JAs. Recent insights into the JAs mediated plant defense cascade and knowledge of key regulators of this will help us to design future crops with increased biotic stress resistance and better adaptability. Higher crop yields might be achieved by increasing the pathogen/insect resistance which can be achieved by manipulating the expression of the key genes involved in JAs biosynthesis and signaling cascades.