Functional Analysis Of DAD1 And DAL Genes In The Wound Induction Of Jasmonic Acid Biosynthesis In Arabidopsis thaliana

Abstract

Jasmonic acid (JA), a plant hormone which induces defense response to pathogen and insect attacks, is synthesized at high level immediately after wounding. We have identified DAD1 as a lipase catalyzing the initial step of JA production at flower opening. However, the JA level in wounded dad1 leaves just slightly decreased than wild type, suggesting that the lipase(s) other than DAD1 must be involved in the wound induction of JA. To identify such lipases, we focused on the DAL genes (DAL1 -DAL6 ), the DAD1 encoding chloroplast-localized lipases, and made multiple knockouts among these genes. In wounded leaves of dad1 dal2 dal3 dal4 quadruple mutant, the JA level was decreased to only a half of wild type. Moreover, the expression level of VSP2 in the leaves was reduced to 10% of wild type. These results suggested that the DAD1 and DALs are responsible for the wound induction of JA.