Li Y, Cao XL, Zhu Y, Yang XM, Zhang KN, Xiao ZY, Wang H, Zhao JH, Zhang LL, Li GB, Zheng YP, Fan J, Wang J, Chen XQ, Wu XJ, Zhao JQ, Dong OX, Chen XW, Chern M, Wang WM.

New Phytol. 2019 Jan 10. doi: 10.1111/nph.15678.

Abstract

miRNAs contribute to plant resistance against pathogens. Previously, we found that the function of miR398b in immunity in rice differs from that in Arabidopsis. However, the underlying mechanisms are unclear. In this study, we characterized the mutants of miR398b target genes and demonstrated that multiple superoxide dismutase genes contribute to miR398b-regulated rice immunity against the blast fungus Magnaporthe oryzae. Out of the four target genes of miR398b, mutations in Cu/Zn-Superoxidase Dismutase1 (CSD1), CSD2 and Os11g09780 (SODX) led to enhanced resistance to M. oryzae and increased H₂ O₂ accumulation. By contrast, mutations in Copper Chaperone for Superoxide Dismutase (CCSD) resulted in enhanced susceptibility. Biochemical studies revealed that csd1, csd2 and sodx displayed altered expression of CSDs and other SOD family members, leading to increased total SOD enzyme activity that positively contributed to higher H₂ O₂ production. In contrast, the ccsd mutant showed CSD protein deletion, resulting in decreased CSD and total SOD enzyme activity. Our results demonstrate the roles of different SODs in miR398b-regulated resistance to rice blast disease, and uncover an integrative regulatory network in which miR398b boosts total SOD activity to up-regulate H₂ O₂ level and thereby improve disease resistance.

See: https://www.ncbi.nlm.nih.gov/pubmed/30632163