Jasmonic acid regulation

DAVIS, J.M., WU, H., COOKE, J.E., REED, J.M., LUCE, K.S., MICHLER, C.H., Pathogen challenge, salicylic acid, and jasmonic acid regulate expression of chitinase gene homologs in pine.. Mol Plant Microbe Interact., 2002,15, 380-387. 

Meyer, A., O. Miersch, C. Buttner, W. Dathe, and G. Sembdner. Occurrence of the plant growth regulator jasmonic acid in plants. J Plant Growth Regul 1984 3 1-8. 

A few of the compounds containing a 5-membered ring system such as jasmonic acid (224) and cucurbic acid (225) were reported to possess growth-regulating properties. These acids are structurally related to prostaglandins which are yet to be detected in the plant kingdom (Figure 12). 

Small molecule carboxylates are an important class of compounds that plants produce to attract pollinators,44 defend against herbivory,45 7 regulate the cell cycle,48,49 and induce defense responses.50 5 Often these compounds are esterified and volatilized. Plants utilize the emission of volatile esters as chemoattractants and signaling molecules. Classes of volatile compounds include the salicylates and jasmonates, which are ubiquitously distributed in the plant kingdom. Jasmonic acid, salicylic acid, and their methyl ester derivatives, are intimately involved in cell regulation and help control such developmental processes as seed germination, flower development, fruit development, and senescence.14,17,53... 

Plants utilize methyljasmonate not only for floral scent but also as a cellular regulator that controls a myriad of plant functions.76 The cis epimer (Fig. 11.3) is believed to be the most biologically active.77 Like methylsalicylate, methyljasmonate and its precursor jasmonic acid have been implicated in the induction of defense-related genes in plants that are damaged by herbivores or challenged by infection.78,79 Application of methyljasmonate either directly to the plant or in a volatilized spray can induce the expression of known pathogenesis-related proteins.80 82... 

Dosage/response experiments then showed that the biological activity resides mainly with the primary product, namely the (3H,7S)-jasmonic acid to a lesser extent with its methyl ester. Jasmonic acid does not bind as the free acid, but as a conjugate with isoleucine to the same receptor as coronatine, a phytotoxin produced by Pseudomonas syringae. In this conjugate, epimerisation at C-7, which is associated with a dramatic loss in activity, is used by the plants to regulate hormone activity. [82]... 

A similar mode of action on the above photosynthetic parameter has been reported about another growth regulator-Jasmonic acid (JA) (10). To a certain extent the action of JA is similar to the inhibiting effect of ABA on the processes of germination and ageing, and also similar in the maner of effect on the stomata and on the protein hydrolysis (14, 17). In its chemical structure and methods of synthesis JA is very close to the group of the prostanoids which, in the case of animals are known to belong to the class of stress-related hormones (19). 

The release of unsaturated fatty acids, particularly 18 3, from membranes by phospholipases is proposed to represent a controlling step, e.g. [199,200]. After this initial event, involvement of small GTP-binding proteins in the regulation of jasmonic acid formation was reported in the pathogenesis-related protein... 

The localization of enzymes of the oxylipin pathway has yet to be unequivocally elucidated. Nonetheless, LOX has been localized in plastids, vacuoles and the cytoplasm, e.g. [1], and in lipid bodies [36,37]. Since enzymes of the jasmonic acid biosynthetic pathway are thought to be localized mainly in plastids, mechanisms must exist to shuttle fatty acids released from the plasma membrane to the plastids. Furthermore, since p-oxidation of fatty acids normally occurs in peroxisomes, transport vesicles that carry the cargo between organelles may exist in plant cells. It is tempting to speculate that there could be fusion or mixing of compartments that contain either enzymes, fatty acids, and/or intermediate products, thus resulting in oxylipin biosynthesis. Intensive research is needed to address these questions as well as the cell-specific and the subcellular localization of oxylipin synthesis and the mechanisms that regulate this process. 

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