J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (8): 1614-1630.DOI: 10.1111/jipb.13322

• Molecular Physiology • Previous Articles     Next Articles

The divergence of brassinosteroid sensitivity between rice subspecies involves natural variation conferring altered internal auto-binding of OsBSK2

Wenchao Yin1†, Lulu Li1†, Zhikun Yu1,2, Fan Zhang1, Dapu Liu1, Hongkai Wu3, Mei Niu1, Wenjing Meng1, Xiaoxing Zhang1, Nana Dong1, Yanzhao Yang1, Jihong Liu1, Yongqiang Liu3, Guoxia Zhang3, Jianlong Xu1, Shimei Wang2, Chengcai Chu3, Qian Qian1 and Hongning Tong1*   

  1. 1 National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
    2 Rice Research Institute of Anhui Academy of Agricultural Sciences, Hefei 230001, China
    3 State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China

    These authors contributed equally to this work.
    * Correspondence: Hongning Tong (tonghongning@caas.cn)
  • Received:2022-03-17 Accepted:2022-06-16 Online:2022-06-28 Published:2022-08-01


Japonica/geng and indica/xian are two major rice (Oryza sativa) subspecies with multiple divergent traits, but how these traits are related and interact within each subspecies remains elusive. Brassinosteroids (BRs) are a class of steroid phytohormones that modulate many important agronomic traits in rice. Here, using different physiological assays, we revealed that japonica rice exhibits an overall lower BR sensitivity than indica. Extensive screening of BR signaling genes led to the identification of a set of genes distributed throughout the primary BR signaling pathway with divergent polymorphisms. Among these, we demonstrate that the C38/T variant in BR Signaling Kinase2 (OsBSK2), causing the amino acid change P13L, plays a central role in mediating differential BR signaling in japonica and indica rice. OsBSK2L13 in indica plays a greater role in BR signaling than OsBSK2P13 in japonica by affecting the auto-binding and protein accumulation of OsBSK2. Finally, we determined that OsBSK2 is involved in a number of divergent traits in japonica relative to indica rice, including grain shape, tiller number, cold adaptation, and nitrogen-use efficiency. Our study suggests that the natural variation in OsBSK2 plays a key role in the divergence of BR signaling, which underlies multiple divergent traits between japonica and indica.

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