J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (4): 871-883.DOI: 10.1111/jipb.13238

• Cell and Developmental Biology • Previous Articles     Next Articles

Mediator complex subunit MED25 physically interacts with DST to regulate spikelet number in rice

Lihao Lin1, Minmin Du1, Shuyu Li1, Chuanlong Sun1, Fangming Wu1, Lei Deng1, Qian Chen2* and Chuanyou Li1*   

  1. 1 State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, The Chinese Academy of Sciences, Beijing 100101, China
    2 State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian 271018, China

    *Correspondences: Chuanyou Li (cyli@genetics.ac.cn, Dr. Li is fully responsible for the distributions of all materials associated with this article); Qian Chen (chenqiangenetics@163.com)
  • Received:2021-11-04 Accepted:2022-02-24 Online:2022-02-25 Published:2022-04-01


Grain number is a flexible trait and contributes significantly to grain yield. In rice, the zinc finger transcription factor DROUGHT AND SALT TOLERANCE (DST) controls grain number by directly regulating cytokinin oxidase/dehydrogenase 2 (OsCKX2) expression. Although specific upstream regulators of the DST–OsCKX2 module have been identified, the mechanism employed by DST to regulate the expression of OsCKX2 remains unclear. Here, we demonstrate that DST-interacting protein 1 (DIP1), known as Mediator subunit OsMED25, acts as an interacting coactivator of DST. Phenotypic analyses revealed that OsMED25-RNAi and the osmed25 mutant plants exhibited enlarged panicles, with enhanced branching and spikelet number, similar to the dst mutant. Genetic analysis indicated that OsMED25 acts in the same pathway as the DST–OsCKX2 module to regulate spikelet number per panicle. Further biochemical analysis showed that OsMED25 physically interacts with DST at the promoter region of OsCKX2, and then recruits RNA polymerase II (Pol II) to activate OsCKX2 transcription. Thus, OsMED25 was involved in the communication between DST and Pol II general transcriptional machinery to regulate spikelet number. In general, our findings reveal a novel function of OsMED25 in DST–OsCKX2 modulated transcriptional regulation, thus enhancing our understanding of the regulatory mechanism underlying DST–OsCKX2-mediated spikelet number.

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