α-Linolenic acid concentration and not wounding per se is the keyregulator of octadecanoid (oxylipin) pathway activity in rice (Oryza sativa L.) leaves

John T. Christeller, Ivan Galis

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Using an invitro system composed of crushed leaf tissues to simulate the wounding response in rice leaves, we established that synthesis of jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) can only occur in unwounded tissue and, in wounded tissue, that only the chloroplast-located section of the octadecanoid pathway is active, resulting in the accumulation of 12-oxo-phytodienoic acid (OPDA). We further showed that OPDA accumulation invitro was inhibited by 90% using the general lipase inhibitor, tetrahydrolipstatin, indicating that production of α-linolenic acid was the rate-limiting step in octadecanoid pathway activity in rice following wounding and the enzyme capacity for an active pathway was already present. We confirmed this result by showing that added α-linolenic acid stimulated OPDA synthesis invitro and stimulated OPDA, JA and JA-Ile synthesis invivo in unwounded tissue. Thus, the response to wounding can be mimicked by the provision of free α-linolenic acid. Our results draw attention to the key importance of lipase activity in initiation of JA and JA-Ile biosynthesis and our lack of knowledge of the cognate lipase(s), lipase substrate identity and mechanism(s) of activation in wounded and unwounded tissue.

Original languageEnglish
Pages (from-to)117-125
Number of pages9
JournalPlant Physiology and Biochemistry
Volume83
DOIs
Publication statusPublished - Oct 2014

Keywords

  • 12-oxo-phytodienoic acid
  • Jasmonic acid
  • Octadecanoid pathway
  • Oryza sativa
  • α-Linolenic acid

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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