Role of Jasmonic acid in plant development and defense responses

JA is mainly helps for defense responses


by msc (agri )

1. Master Seminar I Role of Jasmonic Acid in Plant Development and Defence Response Shashikala PGS17AGR7563 UNIVERSITY OF AGRICULTURAL SCIENCES, DHARWAD College of Agriculture, Vijayapur Department of Crop Physiology

2. flow of seminar Biosynthesis of JA Properties and Functions of JA Introduction Metabolic fate of JA Role of JA in plant defence and development Research findings Conclusion

3. Hormones are chemical messenger, which plays a vital role in controlling the entire life process and other activities in the plants -like seed germination, ripening, growth, and flowering. The term "hormone" is derived from a Greek word meaning “ to stimulate or to enhance an activity" Plant growth regulators are usually defined as organic compounds other than nutrients that in smaller concentration, affects the physiological processes of plants. Plant hormones

4. The application of plant growth regulators in agriculture has been started since 1930 in United States. Ethylene , a naturally occurring harmone, which is the first plant growth regulator being discovered and used successfully for enhancing the flower production in pineapple. Plant growth regulators are charac terized by t heir l ow rates of applic ation, while the high appli cation rates of the same compounds are often considered as herbicide Its toxic effects to human beings are low. Synthet ic substances that mimic such natural ly occurring plant hormones were also produced, since then the use of plant growth regulators has been growing significantly and becoming a major component in modern agriculture.

5. Plant hormones

6. Cell elongation Flower initiation Fruit development Apical dominance cell elongation + cell division Delay leaf senescence Reduces apical dominance. Seed dormancy Morphogenesis. Bud dormancy Stem growth Flowering Auxin (IAA) Cytokinins Gibberellins

7. General growth inhibitor. Causes stomatal closure. Produced in response to stress Inhibits the stem growth Fruit ripening. Leaf abscission Stem swelling Flower petal discoloration Abscisic acid Ethylene

8. INTRODUCTION Jasmonates are cyclo pentanone compounds or Novel plant immune hormones which is derived from α- linolenic acid by the  octadecanoid pathway. It includes group of oxygenated fatty acids which are collectively called as oxylipins . Methyl jasmonate was first isolated from the essential oil of Jasmoinum grandiflorum. Demole et.al.,(1962).Helv.Chim.Acta.45:675-695 First isolated in culture filtrate of fungi Lasiodiplodia theobromae .

9. Jasmonic acid Initial discovery of metyl jasmonates ( MeJA ) as secondary metabolite in essential oils of jasmine. Role of 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 respone against herbivorous insects. Dgl gene is responsible of maintaining levels of JA in Zea mays

10. Jasmonic acid responses (a) Chewing insects (b) Necrotropic pathogens

11. Jasmonic acid JA regulates - Photosynthesis Root and shoot growth Seed germination Development Flowering Reproduction Senescence JA triggers - Defense responses

12. Functions of jasmonic acid Signalling molecules :- Plant development Adaptation to environmental stress Involved in plant defense reactions Hormone :- Senescence Tendril coiling Flower development Leaf abscission Trichome induction-Tomato Mechanotransduction - Bryonia Tuberization - Potato

13. Mechanism of signaling The central feature of JA Signalling is the repression of JA responses JAZ (JASMONATE ZIM DOMAIN) protein family . JAZ proteins function to inhibits the activity of transcription factors responsible for driving the expression of JA responsive target genes . In the absence of JA, JAZ proteins bind to downstream transcription factors and limit their activity. However , in the presence of JA or its bioactive derivatives, JAZ proteins are degraded , freeing transcription factors for expression of genes needed in  stress responses.

14. Mechanism of action of JAs in biotic stress

15. Metabolic fate of JA Formation of amino acid conjugates by a JA conjugate synthase ( JAR1 ) ( Staswick and Tiryaki , 2004) upon adenylation at the carboxylic acid side-chain of JA by the AMP- transferase activity of JAR1. Methylation of JA by a JA-specific methyl transferase ( Seo et al.,2001). Hydroxylation at C-11 or C-12 of the pentenyl side chain and subsequent O- glucosylation ( Sembdner and Parthier , 1993; Swiatek et al., 2004). Decarboxylation of JA to cis-jasmone (Koch et al., 1997). Formation of cucurbic acids by reduction of the keto group of the cyclo pentanone ring ( Sembdner and Parthier , 1993). Formation of jasmonoyl-1-b-glucose, jasmonoyl-1- b- gentiobiose and hydroxyjasmonoyl-1-b-glucose( Swiatek et al., 2004). Conjugation of the ethylene precursor ACC to JA( Staswick and Tiryaki , 2004).

16. Metabolic fate of jasmonic acid . The 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.

17. The highest level of JA are reported in flowers, reproductive tissues and young leaves . The lower levels are found in root and mature leaves .

18. Role of Jasmonic Acid in plant defense and development

19. Root Growth Inhibition Figure 1: JA induces root growth inhibition by stimulating auxin biosynthesis via anthranilate synthase α1(ASA1) and inhibiting the expression of genes encoding the TFs PLETHORA1 (PLT1) and PLT2, which ensure the maintenance and activity of stem cells in the root. Root growth inhibition by 100 mM methyl jasmonate in wild-type (Col) and the JA-insensitive mutant coi1-16 Wasternack and Hause 2013

20. Figure 2: In tuber formation, jasmonates [JA, tuberonic acid (TA) and TA glucoside (TAG)] might act directly after their rise following activity of LIPOXYGENASE 1 (LOX1). Wasternack and Hause 2013. TUBER FORMATION

21. TRICHOME FORMATION Wasternack and Hause 2013.

22. Fig.4 Flower development in tomato. Flower buds, open flowers and mature fruits from wild type and the JA-insensitive mutant jai1. Note the seedless fruits of jai1. Wasternack and Hause 2013. Flower Development

23. Senescence Wasternack and Hause 2013

24. Research findings

25. Jasmonic Acid Induces Tuberization of Potato Stolon Cultured in Vitro Tuberization in stolon cultures. A: Control without tuber formation but a good root development. B: Tuberization under increasing JA concentrations (general absence of roots.) Pelacho et al .(1991)

26. Average number of tubers per stolon obtained after 30 d in culture in a MS medium Pelacho et al .(1991) control 1 1.6 µM kinetin 0.5 µM JA 50 µM JA 5 µM JA 2.3 0.8 %

27. Treatment No. of roots per stolon Fresh wt per tuber(mg) Dry wt per tuber (mg) Control 5.1 11.2 0.6 0.5 µM JA 1.9 26.9 2.6 5.0 µM JA 30.6 2.8 50 µM JA 16.7 1.6 11.6 µM kinetin 13.6 1.9 Effect of JA and Kinetin on Average Values for Number of Roots per Stolon , and FW and DW per Tuber after 30 d in Culture Pelacho et al .(1991)

28. The plant growth regulator methyl jasmonate inhibits aflatoxin production by Aspergillus flavus Aflatoxins are highly toxic and carcinogenic compounds produced by the fungi Aspergillus flavus , A. parasiticus and A. nomius . Aflatoxin levels in crops often rise following exposure to certain stresses such as high temperature and drought (Payne,1992; Sanders e t al., 1993). One factor influencing the production of aflatoxin is the presence of high levels of oxidized fatty acids such as fatty acid hydroperoxides . The aldehydes hexanal , trans-2-hexenal, and trans-2-nonenal , which are hydroperoxide metabolites via hydroperoxide lyase (Vick, 1993), generally inhibit spore germination and aflatoxin production. Tanrikulu et al. ( 1995)

29. The plant growth regulator methyl jasmonate inhibits aflatoxin production by Aspergillus flavus Tanrikulu et al.( 1995)

30. Effects of jasmonates on growth and aflatoxin production of A. flavus in vitro MeJA -treated untreated control Goodrich- Tanrikulu et al.( 1995)

31. 3.Effects of jasmonic acid-induced resistance in rice on the plant brownhopper , Nilaparvata lugens Food assimilated (A) and food ingested (B) of adult female N. lugens on rice after activated with induced resistance by JA (2.5 mM and 5 mM ) and control. Nathan et al .(2009)

32. Effect of induced resistance by JA on nymphal N.lugens Nathan et al .(2009) A -Control, B -2.5 mM JA, C -5 mM JA.

33. Effect of induced resistance by JA on egg and adult female of N. lugens ( A -Control, B -2.5 mM JA, C -5 mM JA). Nathan et al .(2009)

34. Biomass production of JA 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 used.

35. Application of JA 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 after year. Field application of JA may enhance the efficacy of parasitoids and predators as biological control agents .

36. JA seed treatment stimulates the natural anti-pest defences 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. 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).

37. conclusion 48

38. 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 in to 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

39. THANK YOU Nature has blessed me with Defense mechanism