Disease Resistance against Magnaporthe grisea in Transgenic Rice Lines with Suppression of Allene Oxide Cyclase Gene or 12-oxo-Phytodienoic Acid Reductase Genes

Abstract

Linolenic acid (18:3) is a source for various oxidized metabolites, such as jasmonic acid (JA) and its precursor 12-oxo-phytodienoic acid (OPDA), which are involved in defense responses to pathogen infection as signaling molecules. OPDA is synthesized by allene oxide cyclase (AOC), and then is converted to JA by OPDA reductase (OPR). To study roles of JA and OPDA in rice disease resistance to a blast fungus Magnaporthe grisea, we generated an OPDA/JA-deficient line (AOCRi) and a JA-deficient line (OPRWRi) with suppression of the AOC or OPR genes. The levels of the disease resistance in the AOCRi and OPRWRi lines were equal to that in wild-type plants. Furthermore, in the two lines, two pathogenesis-related genes (PBZ1 and PR1b) were normally induced after inoculation with M. grisea. These results suggest that the disease resistance to M. grisea in rice is induced without any relation to JA and OPDA synthesis.