Poster: Lipids & Related Molecules

Abs # 854: Expression of secreted phospholipase A₂ genes in Arabidopsis

Presenter:	Nishimura, Kohji , knishimu@life.shimane-u.ac.jp
Authors	Nishimura, Kohji  (A)   Muta, Takahiro  (A)   Daisuke, Eguchi  (A)   Mitsuo, Jisaka  (A)   Tsutomu, Nagaya  (A)   Kazushige, Yokota  (A)
Affiliations:	(A): Department of Life Science and Biotechnology, Shimane University

Phospholipases A₂ (PLA₂) are enzymes which catalyze the hydrolysis of phospholipids at the sn-2 fatty acyl bond to release free fatty acids and lysophospholipids. In plant, PLA₂s form a large family of structurally related enzymes like animal kingdom, which is composed of secreted PLA₂ (sPLA₂), calcium-independent PLA₂, and patatin-like@PLA₂, but not cytosolic PLA₂. Plant PLA₂s have been demonstrated to be involved in various biological processes including lipid digestion, membrane repair, defense response to pathogen and wounding, and signal transduction. In this study, we investigated the involvement of sPLA₂ in jasmonate signaling. Arabidopsis plant has several sPLA₂ related genes. The exposure of methyl jasmonate caused the stimulatory expression of almost all the sPLA₂ genes in suspension-cultured Arabidopsis cells as well as jasmonate-inducible genes such as lipoxygenase and vegetative storage protein. Furthermore most of sPLA₂ genes were expressed in several tissues such as roots, stems, and leaves in Arabidopsis plant grown under normal conditions. These data suggested that PLA₂ could be involved in jasmonate biosynthesis by positive feedback manner, and activation of sPLA₂ activity might be not only transcriptionally but also post-translationally regulated by external signals and cellular metabolites.