Abstract
Jasmonic acid (JA) is a plant hormone responsible for the defense from pathogen and insect attacks. It is synthesized at high level immediately after the mechanical wounding of plant tissue. The initial step of JA biosynthesis is a lipolytic reaction by lipase(s) that releases linolenic acid from chloroplast membrane lipids. One of these lipases is the DAD1 involved in the JA production at flower opening, but the dad1 mutant fully generates JA after wounding, suggesting that the lipase other than DAD1 is responsible for the wound induction. In the Arabidopsis genome, there are 11 lipase genes highly homologous to the DAD1, and six of them (DAL1-DAL6) are predicted to be chloroplast proteins. We examined the expression of these genes and showed that the DAL2, 3, 4 are constitutively expressed in leaves, whereas the DAL6 and DAD1 are induced after wounding. Making multiple knockouts of these genes is in progress.
