Induction of 12-Oxo-Phytodienoic Acid in Wounded Plants and Elicited Plant Cell Cultures

Abstract

Jasmonic acid (jA) is rapidly biosynthesized from a-linolenic acid in plants upon contact with pathogens or wounding, and triggers gene activation, leading to the synthesis of defensive secondary metabolites and proteins. Despite the recent finding that its precursor, 1 2-0x0-phytodienoic acid (PDA), is a more powerful inducer of gene activation, interest has focused so far almost exclusively on jA.A validated negative chemical ionization-gas chromatography-mass spectrometry method has been developed that allows the simultaneous quantification of endogenous 1 2-0x0-PDA and JA in plant tissues. In six out of eight plant species tested maximal levels of 12-0x0-PDA exceeded peak levels of JA by approximately 3-to 5-fold after elicitation with a yeast cell wall preparation or when plants were wounded. These experiments support the hypothesis that 12-0x0-PDA acts as the predominant jasmonate signal in most plants, whereas JA remains an active metabolite of its precursor. Furthermore, JA but not 12-0x0-PDA was shown to be secreted into the medium from cultured plant cells, suggesting that jA may also act as an intercellular signal.

Identification, Separation, and Characterization of Acyl-Coenzyme A Dehydrogenases Involved in Mitochondrial β-Oxidation in Higher Plants1

“…For instance, conventional ␤-oxidation of the C 18 precursor to jasmonate would involve 15 steps, including the initial activation of the carboxyl group and the final release of jasmonate by acylCoA thioesterase activity (Mueller, 1997). The compartment in which these transformations take place is not known (Mueller, 1997;Parchmann et al, 1997). It would obviously be of great interest to determine whether the enzymes involved are mitochondrial or peroxisomal.…”

Plant Lipoxygenases. Physiological and Molecular Features

“…As shown in Table I, the function of LOX in the defense against pests seems to be related to the synthesis of a number of different compounds with signaling functions (Creelman and Mullet, 1997;Parchmann et al, 1997), antimicrobial activity (Croft et al, 1993;Weber et al, 1999), or to the development of the HR (Rustérucci et al, 1999).…”

“…JA and OPDA levels increase upon wounding (Creelman and Mullet, 1997;Parchmann et al, 1997). JA or OPDA treatment induces the synthesis of molecules that function in the defense against herbivores (Creelman and Mullet, 1997).…”

The Jasmonate Signal Pathway

“…JA signaling can be induced by a range of abiotic stresses, including osmotic stress (Kramell et al, 1995), wounding, drought, and exposure to "elicitors," which include chitins, oligosaccharides, oligogalaturonides (Doares et al, 1995), and extracts from yeast (Parchmann et al, 1997;Leon et al, 2001). JA biosynthesis in Arabidopsis is also regulated by cues in the developing stamen, where jasmonic acid is required for pollen development.…”