82. イネのJAシグナル伝達経路におけるJA応答性bHLH型転写因子RERJ1の役割(口頭発表,植物化学調節学会第46回大会)

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The plant hormone jasmonic acid (JA) has been recognized as a signal molecule that is produced in response to various stresses such as wounding and pathogen attack and that mediates defense reactions. We previously identified the JA-early responsive bHLH factor RERJ1 whose overexpression caused the up-regulation of many pathogenesis-related (PR) genes in rice cells and severe growth inhibition in rice plants. We reported in the last meeting that RERJ1 is induced by JA synthesized locally around the site of injury, and subsequently up-regulates the expressions of many PR genes and insect defense-related genes based on data obtained by histochemical analyses of RERJ1 promoter-GUS transgenic plants and characterization of the RERJ1 Tos17 mutant (rerj1-tos). Further investigations of the mutant revealed that JA-dependent inductive expressions of JAZ family genes, which encode important repressor proteins of JA signaling, were repressed in the rerj1-tos mutant after wounding. In a yeast two-hybridization assay we found interaction of RERJ1 with one of the rice JAZ proteins. In Arabidopsis it is known that the expression of JAZ genes is induced by bHLH factor MYC2 in a JA-dependent manner, and MYC2 activity is suppressed by interaction with JAZ proteins. Therefore we are investigating the interaction of RERJ1 with a rice MYC2 ortholog now, and will discuss roles of RERJ1 in rice JA signaling.
2011-10-03