Nitric Oxide is Involved in Methyl Jasmonate- induced Lateral Root Formation in Rice

Abstract

In this study, we examined the effect of methyl jasmonate (MJ) on lateral root (LR) formation in rice. Application of MJ to rice seedlings induced LR formation. This effect was blocked by the nitric oxide (NO) scavenger 2-(4carboxyphenyl)-4,4,5,5- tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO). Nitric oxide was detected by the specific fluorescence probe 4-amino-5-methylamino-2',7'-difluoroflorescein diacetate. Methyl jasmonateinduced NO fluorescence was specifically suppressed by cPTIO. Nitrate reductase (NR) inhibitor sodium tungstate completely inhibited MJ-induced LR formation and NO fluorescence. However, NO synthase inhibitor NG-nitro-L-arginine methyl ester hydrochloride partially reduced MJ-promoted LR formation and NO generation, indicating that the MJ-induced NO generation was related to the NR activity. Moreover, NO generation induced by MJ was localized in root area corresponding to LR emergence. Our results suggest that MJ-promoted LR formation in rice is mediated by the NO signaling pathway.