بررسی اثر ریبوفلاوین بعنوان فعال کننده مکانیسمهای دفاعی گیاه برنج علیه بیماریهای رایزوکتونیایی

Abstract

Abstract In this study, the role of riboflavin (vitamin B2) as a defense activator in rice plant against Rhizoctonia diseases was investigated. Following application of riboflavin, rice plants developed systemic resistance to the pathogen and riboflavin did not have any direct effect on the growth pathogens and did not cause phytotoxicity on plants. The necessity of the time interval between riboflavin application and inoculation of pathogen for reduction of disease progress clearly indicates that riboflavin protects rice against R. solani by inducing plant defense responses and induction of resistance. This case was further confirmed by investigating the expression of defense genes, including cationic rice perroxidase (PO-C1), phenylalaninr ammonia-lyase (PAL), and lipoxygenase (LOX). Results revealed elevated levels of LOX and PO-C1 expression in riboflavin-treated plants especially after inoculation with the pathogen. Induction of resistance in plant even after 20 days post-treatment with riboflavin reveales that the vitamin is effective for induction of more durable resistance compared to other activators of plant defense system. Our findings demonstrate that using riboflavin as a plant defense activator is a new, simple, and environmentally safe strategy that could be used to control Rhizoctonia sheath diseases of rice. Key words: Rhizoctonia spp., Rice, Riboflavin, Induced Resistance, Expression of Defense-Related Genes