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

Abstract

We show that a rice GRAS family protein, CIGR2, is a bonafide transcriptional activator, and through this function, targets the B-type heat shock protein-encoding gene OsHsf23 (Os09g0456800). CIGR2 (Os07g0583600) is an N-acetylchitooligosaccharide elicitor-responsive gene whose activity, through the direct transcriptional control of OsHsf23, is required for mediating hypersensitive cell death activation during pathogen infection. RNAi lines of CIGR2 and OsHsf23 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 OsHsf23.

Graphical abstract

N-Acetylchitooligosaccharides-responsive CIGR2 suppresses cell death of rice in cooperation with OsHsf23.

Key words:

• GRAS family
• heat shock transcription factor
• cytoplasmic granulation
• rice

View correction statement:

Corrigendum

Acknowledgments

The authors are grateful to Dr Takashi Aoyama of Kyoto University (Japan) and Dr Nam-Hai Chua of Rockfeller University (USA) for providing us with a plasmid for pTA7001. We also thank Dr Masaru Ohme-Tanagi of The National Institute of Advanced Industrial Science and Technology (Japan) and late Dr Ko Shimamoto of The Nara Institute of Technology (Japan) for providing us with a plasmid for reporter assay and pANDA vector, respectively.

Notes

Abbreviations: SD, standard deviation; hpi, hs post-inoculation.