J Integr Plant Biol ›› 2024, Vol. 66 ›› Issue (12): 2754-2771.DOI: 10.1111/jipb.13783  cstr: 32098.14.jipb.13783

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  • 收稿日期:2024-02-06 接受日期:2024-09-19 出版日期:2024-12-01 发布日期:2024-12-07

The receptor-like cytoplasmic kinase OsBSK1-2 regulates immunity via an HLH/bHLH complex

Xun Wang1, Zhijuan Diao1, Chang Cao1, Yan Liu1, Na Xia1, Youlian Zhang1, Ling Lu1, Fanyu Kong1, Houli Zhou1, Lizhe Chen1, Jing Zhang1, Bangsheng Wang1, Ronghua Huang2, Dingzhong Tang1* and Shengping Li1,3   

  1. 1. State Key Laboratory of Ecological Control of Fujian‐Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
    2. College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
    3. Fujian Provincial Key Laboratory of Crop Breeding by Design, Fujian Agriculture and Forestry University, Fuzhou 350002, China
    *Correspondences: Dingzhong Tang (dztang@fafu.edu.cn); Shengping Li (lishun1981@126.com, Dr. Li is fully responsible for the distribution of all materials associated with this article)
  • Received:2024-02-06 Accepted:2024-09-19 Online:2024-12-01 Published:2024-12-07
  • Supported by:
    This work was supported by National Key Research and Development Program of China (2022YFF1001500) and Guiding Project of Fujian Science and Technology Plan (2022N0005).

Abstract: Plants need to fine-tune defense responses to maintain a robust but flexible host barrier to various pathogens. Helix-loop-helix/basic helix-loop-helix (HLH/bHLH) complexes play important roles in fine-tuning plant development. However, the function of these genes in plant immunity and how they are regulated remain obscure. Here, we identified an atypical bHLH transcription factor, Oryza sativa (Os)HLH46, that interacts with rice receptor-like cytoplasmic kinase (RLCK) Os BRASSINOSTEROID-SIGNALING KINASE1-2 (OsBSK1-2), which plays a key role in rice blast resistance. OsBSK1-2 stabilized OsHLH46 both in vivo and in vitro. In addition, OsHLH46 positively regulates rice blast resistance, which depends on OsBSK1-2. OsHLH46 has no transcriptional activation activity and interacts with a typical bHLH protein, OsbHLH6, which negatively regulates rice blast resistance. OsbHLH6 binds to the promoter of OsWRKY45 and inhibits its expression, while OsHLH46 suppresses the function of OsbHLH6 by blocking its DNA binding and transcriptional inhibition of OsWRKY45. Consistent with these findings, OsWRKY45 was up-regulated in OsHLH46-overexpressing plants. In addition, the oshlh46 mutant overexpressing OsbHLH6 is more susceptible to Magnaporthe oryzae than is the wild type, suggesting that OsHLH46 suppresses OsbHLH6-mediated rice blast resistance. Our results not only demonstrated that OsBSK1-2 regulates rice blast resistance via the OsHLH46/OsbHLH6 complex, but also uncovered a new mechanism for plants to fine-tune plant immunity by regulating the HLH/bHLH complex via RLCKs.

Key words: Magnaporthe oryzae, OsbHLH6, OsBSK1‐2, OsHLH46, rice, rice blast resistance, RLCK

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