Jasmonic, acid synthesis

Abscisic-acid-deficient tomato and potato plants do not respond to mechanical wounding by accumulation of pin 2 mRNA, therefore providing evidence that ABA is involved in wound response. It was demonstrated that the site of action of jasmonic acid is located downstream to the site of action of ABA. The fact that tomato leaves of ABA-deficient plants showed increased levels of jasmonic acid, similar to those found in wild-type plants after treatment with 18 3, supports a hypothesis that during tissue injury ABA might lead to the activation of jasmonic acid synthesis through activation of a fatty-acid-releasing enzyme such as lipase [186]. 

Exposure to volatile stress signals such as ethylene and jasmonic acid can induce the synthesis and accumulation of high levels of phenolic compounds. The effect is not readily apparent because the accumulated phenolic compounds remain sequestered in organelles within the induced cells. However, increased membrane permeability resulting from even a minor injury or stress can result in levels of discoloration that are abnormally high for that cultivar. 

Blechert and co-workers have also reported the application of cross-metathesis to the synthesis of jasmonic acid derivatives containing modified alkene side chains [28]. Molybdenum or ruthenium catalysed cross-metathesis of acetal 20 with various alkenes gave the desired cross-metathesis products in high yields (Eq. 21) (Table 2). 

Farmer EE, Ryan CA, Octadecanoid precursors of jasmonic acid activate the synthesis of wound-inducible proteinase inhibitors, Plant G //4 129—134,1992. 

BALDWIN, I.T., SCHMELZ, E.A., OHNMEISS, T.E., Wound induced changes in root and shoot jasmonic acid pools correlate with induced nicotine synthesis in Nicotiana sylvestris. J. Chem. Extol., 1994,20,2139-2158. 

Scheme 10 Synthesis of ep/ -jasmonic acid starting with (R)-25.

Recently, the protected tuberonic acid was synthesized by using the method shown in Scheme 10 and deprotection was studied with success to afford tuberonic acid for the first time (Scheme 13)846 Through the synthesis it was revealed that tuberonic acid and its derivative are liable to epimerization more easily than epi-jasmonic acid. In addition, exposure of tuberonic acid to NaOH in aqueous MeOH produced 12-hydroxyjas-monic acid. 

Jasmonic acid has two available sites for the synthesis of hapten-protein conjugates (Fig. 

The methyl ester of jasmonic acid (methyl 3-oxo-2-(2 -pentenyl)-cyclopentaneacetate) is also known as both an active plant hormone and an important fragrance and flavor component with sweet-floral and jasmine-like aroma notes (13). Methyl jasmonate induces plant systems to provide defense from microbial infection, and is a secondary synthesis product of plants. Methyl jasmonate was also isolated from the Oriental fruit moth, Grapholitha molesta as a part of the male sex hormone (7,75). The authors demonstrated that the volatile form of jasmonic acid, methyl jasmonate, is a major signal molecule for inter- and intra species communications. Methyl jasmonate is expected to have... 

Activity Via the gas phase [ 10 nL ( )-( 1 )/L] it is a potent inducer of proteinase-inhibitor proteins in some species of Solanaceae and Fabaceae . After uptake in the cells it is presumably rapidly hydrolysed to jas-monic acid [C,2H,g03, Mr 210.27, viscous oil, bp. 125 °C (0.13 Pa)], a ubiquitous, intracellular, plant signal substance which stimulates the synthesis of special proteins and induces the plant s defensive reaction via a gene activation . De novo synthesis of (3/f,75)-(-t)-jasmonic acid and an increase in the intracellular concentration of (3/f,75)-(-F)-jasmonic acid from 1-10 ng/g (dry weight) by one to three orders of magnitude occur within a few minutes, e.g., after contact with microbial cell wallswounding, and in shoot spiralization Exogenous application of (methyl)jas-... 

An efficient enantiomeric synthesis of (-)-methyl jasmonate [16] and (-l-)methyl epijasmonate [17] has been reported. The procedure makes use of a chiral cyclopen-tanoid building block that can easily be prepared from tartaric acid by phosphorus ylid chemistry (75). Jasmonic acid was also prepared by mixed Kolbe electrolysis (76). Methyl 3-methyljasmonate was synthesized from methyl jasmonate via methyl 3,7-dehydrojasmonate (77). 

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). 

When methyl jasmonate was applied to the surface of tomato plants, the synthesis of a defensive proteinase inhibitor protein was induced, not only in the plant to which the application was made but also in nearby plants. In subsequent studies, this compound was shown to have a similar effect with plants of other families as well (Farmer and Ryan, 1990 Pearce et al., 1991). In a series of experiments, it was demonstrated that methyl jasmonate can be a component of interplant communication systems. Octadecanoid precursors of jasmonic acid were able to activate the synthesis of wound-inducible proteinase inhibitors (Crombie and Mistry, 1991 Farmer and Ryan, 1992). Jasmonic acid is a signal transducer in elicitor-induced plant cultures of Rauvolfia canescens and Eschscholtzia californica. Tissue cultures of 36 species of plants could be induced to accumulate second-... 

Crombie, L. and K. M. Mistry, Synthesis of 12-oxophytodienoic acid (12-oxoPDA) and the compounds of its enzymic degradation cascade in plants, OPC-8 0, -6 0, -4 0, and -2 0 epi-jasmonic acid), as their methyl esters, J. Chem. Soc. Perkin Trans. I, 1981-1991 (1991). 

More than 30 years ago it was reported that flaxseed homogenates convert 13-HpOTrE into a- and -y-ketols, and the enzyme responsible for this reaction was called hydroperoxide isomerase [54]. Later studies indicated that this reaction was actually a two-step process, consisting of an enzyme-catalysed dehydration of the hydroperoxy fatty acid to a rather unstable allene oxide followed by a non-enzymic hydrolysis [55,56]. The enzyme responsible for allene oxide synthesis has been purified and shown to be a cyt E-450 isoform [57]. As an alternative to hydrolysis, the allene oxide may undergo enzymic cyclization forming 12-oxo-phytodienoic acid. This compound is subsequently converted into jasmonic acid, a phytohormone implicated in the reaction of higher plants to a number of stimuli, such as wounding, fungal elicitation, mechanical forces and osmotic stress [54]. 

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