The elicitor-responsive gene for a GRAS family protein, <i>CIGR2</i>, suppresses cell death in rice inoculated with rice blast fungus via activation of a heat shock transcription factor, <i>OsHsf23</i>

<p>We show that a rice GRAS family protein, CIGR2, is a <i>bonafide</i> transcriptional activator, and through this function, targets the B-type heat shock protein-encoding gene <i>OsHsf23</i> (Os09g0456800). <i>CIGR2</i> (Os07g0583600) is an <i>N</i>-acetylchitooligosaccharide elicitor-responsive gene whose activity, through the direct transcriptional control of <i>OsHsf23</i>, is required for mediating hypersensitive cell death activation during pathogen infection. RNAi lines of <i>CIGR2</i> and <i>OsHsf23</i> similarly exhibited the higher level of granulation in the epidermal cells of leaf sheath inoculated with an avirulent isolate of rice blast fungus. Interestingly, we did not observe altered levels of resistance, suggesting that CIGR2 suppresses excessive cell death in the incompatible interaction with blast fungus via activation of <i>OsHsf23</i>.</p> <p><i>N</i>-Acetylchitooligosaccharides-responsive <i>CIGR2</i> suppresses cell death of rice in cooperation with <i>OsHsf23</i>.</p

Overexpression of TIFY genes promotes plant growth in rice through jasmonate signaling

<p>Because environmental stress can reduce crop growth and yield, the identification of genes that enhance agronomic traits is increasingly important. Previous screening of full-length cDNA overexpressing (FOX) rice lines revealed that OsTIFY11b, one of 20 TIFY proteins in rice, affects plant size, grain weight, and grain size. Therefore, we analyzed the effect of <i>OsTIFY11b</i> and nine other TIFY genes on the growth and yield of corresponding TIFY-FOX lines. Regardless of temperature, grain weight and culm length were enhanced in lines overexpressing TIFY11 subfamily genes, except <i>OsTIFY11e.</i> The TIFY-FOX plants exhibited increased floret number and reduced days to flowering, as well as reduced spikelet fertility, and <i>OsTIFY10b</i>, in particular, enhanced grain yield by minimizing decreases in fertility. We suggest that the enhanced growth of TIFY-transgenic rice is related to regulation of the jasmonate signaling pathway, as in <i>Arabidopsis.</i> Moreover, we discuss the potential application of TIFY overexpression for improving crop yield.</p