Functional analysis and signal transduction of an elicitor responsive gene, CIGR2 of GRAS family in rice plant

Abstract

N-acetylchitooligosaccharides (GN7) elicit a set of defense responses in suspension-cultured rice cells (Oryza sativa). We previously reported the isolation of an elicitor responsive gene, CIGR2 cording for a GRAS family protein in rice and analyzed the detailed mode of expression. We have suggested that CIGR2 negatively regulated cell death when inoculated rice blast fungus, Magnaporthe grisea, and a heat shock transcription factor (HSF) was a downstream gene of CIGR2. To study the role of CIGR2 in defense, we generated CIGR2-RNAi callus of transgenic rice and assessed the cell death. The level of cell death before or after addition of GN7 was higher in RNAi cells than control cells, indicating that CIGR2 negatively regulates cell death. To find the direct regulator of HSF, we performed yeast one-hybrid analysis, and identified a Myb transcription factor as a regulator of expression of HSF gene.