Plant compounds, jasmonic acid

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... 

The relationship between endogenous levels of jasmonic acid and related compounds and tuberization was investigated in plant tissues. Jasmonic acid was found to be in foliage, stolons, roots and tuber periderm in potato [59]. In Jerusalem artichoke, jasmonic acid in the leaves of young plants was very high but decreased... 

VOC emissions from tobacco plants exposed to ozone were investigated with PTR-MS in conjunction with GC-MS, and the formation of volatile Ce emissions was found to be inversely proportional to the O3 flux density into the plants [57]. Jasmonic acid, a signaling compound with a key role in both stress and development in plants who elicits the emission of VOCs, was sprayed on the leaves of the Mediterranean tree species Q. ilex, and the emissions and uptake of VOCs were detected with PTR-MS and GC-MS after a dark-light transition [58]. Monoterpene and methyl salicylate emissions were enhanced and formaldehyde foliar uptake decreased significantly 24 h after the jasmonic add treatment. The release of VOCs from eucalypt as a function of temperatures from ambient to combustion were analyzed by PTR-MS, GC-MS, and direct analysis in real time (DART) MS [59]. The biogenic VOCs seem to provide a protection against high temperatures [60] and oxidation stress [61]. 

Phospholipases A and A2 release free fatty acids which aie the precuisors of a myiiad of oxygenated compounds derived from arachidonic acid in animal cells and from linoleic or linolenic acids in plant cells (jasmonic acid or traumatic acid for examples) [13]. 

Egg-deposition also can induce the host plant to emit volatiles that attract egg parasitoids. For example, egg deposition by the elm leaf beetle (Xantho-galeruca luteola) causes its host plant, the field elm (Ulmus minor), to release a blend of mostly terpenoids that attract the egg parasitoid Oomyzus galleru-cae (Eulophidae) [ 86]. Although the specific compounds that initiate the volatile emission and that attract the egg parasitoid are unknown, the host plant response can be induced with jasmonic acid. 

In plants the 13-hydroperoxide produced from linolenic acid by lipoxygenase (Sect. 23.4.1.2) can be converted to the allene oxide by allene oxide synthase followed by cyclisation, reduction and -oxidation to form jasmonic acid, an important plant growth factor the corresponding methyl jasmonate is a valuable flavour and fragrance compound that imparts a sweet-floral, jasmine-like note... 

The ISR response is triggered by infection of plant roots by specific strains of plant growth-promoting rhizobacteria (PGPRs) and is mediated sequentially by jasmonic acid and ethylene within the plant, but does not result in the accumulation of SA or PRPs [53]. In addition, the ISR response is limited by the ability of the PGPRs to induce ISR in specific plant species and genotypes [54, 55]. Antipathogenic compounds produced by ISR have yet to be identified. The induction of SAR appears to inhibit ISR response. 

In plants a-dioxygenases (Chapter 18) convert free fatty acids into 2(R)-hydroperoxy derivatives (Eq. 7-3, step d).32a These may be decarboxylated to fatty aldehydes (step e, see also Eq. 15-36) but may also give rise to a variety of other products. Compounds arising from linoleic and linolenic acids are numerous and include epoxides, epoxy alcohols, dihydroxy acids, short-chain aldehydes, divinyl ethers, and jasmonic acid (Eq. 21-18).32a... 

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). 

The number of known plant hormones is fewer than the number of mammalian hormones. The number of plant hormones has increased since the publication of the previous edition of the book Comprehensive Natural Products Chemistry in 1998 BRs are added to the plant hormone group, and the group of jasmonic acid-related compounds, a group of peptides, and strigolactone are also included. 

Salicylic acid 11.49 is another signaling molecule in the plant s response. The amount of jasmonic acid rises in 5 min after the insect begins feeding on the tobacco plant. The acid reaches the roots in 2 h and a flush of nicotine reaches the leaves (up to 120 mg/g leaf) in 7 h. Both of these acids can trigger the release of volatile compounds from the plant. These include not only terpenes, but also methyl jasmonate and methyl salicylate, which can signal nearby plants to mount their defenses against attack.183 Methyl jasmonate also inhibits the sprouting of potatoes.184... 

Jasmonic acid (1) and its related compounds which are classified as cyclopentane fatty acids are distributed widely in higher plants [1] and in some micro-organisms [2] (Fig. 1). 

Jasmonic acid was first discovered as its methylester (2) an odoriferous compound from the essential oil of jasmine (Jasminum grandiflomm L.) [3], Early interest in this compound centered on its fragrant properties but recently, jasmonic acid and its methyl ester have fascinated plant physiologists and molecular biologists because they have been shown to possess hormonal activity [4], can act as a senescence-promoting substance [5], and can induce JIP (jasmonate induced proteins) [6] and soybean vegetative storage proteins [7],... 

Metabolism and transport of jasmonic acid in potato plants were studied [47]. The C-labelled compound applied to the leaves was metabolised to a tuberonic acid... 

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