J Integr Plant Biol ›› 2021, Vol. 63 ›› Issue (12): 2043-2057.DOI: 10.1111/jipb.13174

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  • 收稿日期:2021-07-17 接受日期:2021-09-24 出版日期:2021-12-01 发布日期:2021-12-29

OsMKKK70 regulates grain size and leaf angle in rice through the OsMKK4-OsMAPK6-OsWRKY53 signaling pathway

Zhiqi Liu1,2†, Enyang Mei3,4†, Xiaojie Tian3†, Mingliang He3,4, Jiaqi Tang3,4, Min Xu3,4, Jiali Liu1,2, Lu Song3,4, Xiufeng Li3, Zhenyu Wang3, Qingjie Guan1,2*, Qijiang Xu1,2,5* and Qingyun Bu3,6*   

  1. 1 Key Laboratory of Saline‐alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin 150040, China
    2 College of Life Science, Northeast Forestry University, Harbin 150040, China
    3 Northeast Institute of Geography and Agroecology, Key Laboratory of Soybean Molecular Design Breeding, CAS, Harbin 150081, China
    4 University of Chinese Academy of Sciences, Beijing 100049, China
    5 School of Laboratory Medicine, Youjiang Medical University for Nationalities, Baise 533000, China
    6 The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China

    †    These authors contributed equally to this work.
    *Correspondences: Qingjie Guan (guanqingjie@nefu.edu.cn); Qijiang Xu (qijiangxu@nefu.edu.cn); Qingyun Bu (buqingyun@iga.ac.cn, Dr. Bu is responsible for the distribution of the materials associated with this article)
  • Received:2021-07-17 Accepted:2021-09-24 Online:2021-12-01 Published:2021-12-29

Abstract: Grain size and leaf angle are key agronomic traits that determine final yields in rice. However, the underlying molecular mechanisms are not well understood. Here we demonstrate that the Oryza sativa Mitogen Activated Protein Kinase Kinase Kinase OsMKKK70 regulates grain size and leaf angle in rice. Overexpressing OsMKKK70 caused plants to produce longer seeds. The osmkkk62/70 double mutant and the osmkkk55/62/70 triple mutant displayed significantly smaller seeds and a more erect leaf angle compared to the wild type, indicating that OsMKKK70 functions redundantly with its homologs OsMKKK62 and OsMKKK55. Biochemical analysis demonstrated that OsMKKK70 is an active kinase and that OsMKKK70 interacts with OsMKK4 and promotes OsMAPK6 phosphorylation. In addition, the osmkkk62/70 double mutant showed reduced sensitivity to Brassinosteroids (BRs). Finally, overexpressing constitutively active OsMKK4, OsMAPK6, and OsWRKY53 can partially complement the smaller seed size, erect leaf, and BR hyposensitivity of the osmkkk62/70 double mutant. Taken together, these findings suggest that OsMKKK70 might regulate grain size and leaf angle in rice by activating OsMAPK6 and that OsMKKK70, OsMKK4, OsMAPK6, and OsWRKY53 function in a common signaling pathway that controls grain shape and leaf angle.

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