RSI1/FLD is a positive regulator for defense against necrotrophic pathogens

Publication date: Available online 6 April 2019Source: Physiological and Molecular Plant PathologyAuthor(s): Vijayata Singh, Deepjyoti Singh, Janesh Kumar Gautam, Ashis Kumar NandiAbstractThe reduced systemic immunity 1 (rsi1) mutant of Arabidopsis (allelic to fld; flowering locus D) is essential for systemic acquired resistance (SAR). RSI/FLD codes for putative histone-demethylase and modulates flowering and defense response. The rsi1/fld mutants are defective in systemic SA accumulation upon pathogen challenge and fail to respond to the SAR signals in the distal tissues. However, the role of RSI1/FLD in ethylene (ET)-jasmonic acid (JA) signaling was not known. Here we show that expression of RSI1/FLD is induced by methyl-jasmonate (MeJA). The rsi1 mutants are hyper-susceptible to necrotrophic pathogens Botrytis cinerea and Alternaria alternata. In contrary to the susceptibility phenotypes, these mutants are not defective in expression of ET/JA-inducible genes such as PR3, PDF1.2, ERF1, Thi1.2, and ORA59. However, pathogen-induced expression of MYC2 and VSP2 genes are compromised in the rsi1 mutant. Germination of seedlings in the presence of MeJA or amino-carboxy-cyclopropane (ACC, ET precursor) suggest that rsi1/fld mutants are partially defective in JA signaling but hyperactive in ethylene signaling. The results altogether demonstrate novel roles of FLD in controlling plant immune responses against necrotrophic pathogens.
Source: Physiological and Molecular Plant Pathology - Category: Molecular Biology Source Type: research