Abstract
In rice, the physiological role of jasmonic acid (JA), which is assumed to play an important role as a signal molecule in defense responses to insect herbivory in dicotyledonous plants, has remained unclear. The synthesis of linolenic acid (LA), the precursor of JA, in rice is catalyzed by two plastidial ω-3 fatty acid desaturases encoded by two genes, FAD7-1 and FAD7-2. To determine the role of JA, we generated transgenic rice in which the expression of both FAD7-1 and FAD7-2 is suppressed by RNA interference method. LA content in leaves of the FAD-suppressed transformant (F7Ri) was reduced to approximately 13% of the wild-type level. The wound induction of a wound- and JA-responsive gene, JAmyb, was strongly suppressed in F7Ri. From these results, it was inferred that the reduction of LA content in F7Ri affected the wound-induced JA biosynthesis and hence the wound induction of JAmyb.
