J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (11): 1967-1981.DOI: 10.1111/jipb.13168

• Molecular Physiology • Previous Articles     Next Articles

Arabidopsis cryptochrome 1 promotes stomatal development through repression of AGB1 inhibition of SPEECHLESS DNA-binding activity

Xiaoli Cao1, Pengbo Xu2, Yao Liu3, Guangqiong Yang3, Minqing Liu3, Li Chen3, Yingyu Cheng3, Peng Xu1, Langxi Miao1, Zhilei Mao3, Wenxiu Wang3, Shuang Kou3, Tongtong Guo3* and Hong‐Quan Yang3*   

  1. 1 State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China
    2 Department of Plant Sciences, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
    3 Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China

    *Correspondences: Tongtong Guo (ttguo@shnu.edu.cn); Hong‐Quan Yang (hqyang@shnu.edu.cn, Dr. Yang is responsible for the distribution of the materials associated with this article)
  • Received:2021-05-10 Accepted:2021-08-31 Online:2021-09-01 Published:2021-11-01

Abstract: Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabidopsis, cryptochrome 1 (CRY1) and the G-protein β subunit AGB1 act antagonistically to regulate stomatal development. The molecular mechanism by which CRY1 and AGB1 regulate this process remains unknown. Here, we show that Arabidopsis CRY1 acts partially through AGB1, and AGB1 acts through SPEECHLESS (SPCH), a master transcription factor that drives stomatal initiation and proliferation, to regulate stomatal development. We demonstrate that AGB1 physically interacts with SPCH to block the bHLH DNA-binding domain of SPCH and inhibit its DNA-binding activity. Moreover, we demonstrate that photoexcited CRY1 represses the interaction of AGB1 with SPCH to release AGB1 inhibition of SPCH DNA-binding activity, leading to the expression of SPCH-target genes promoting stomatal development. Taken together, our results suggest that the mechanism by which CRY1 promotes stomatal development involves positive regulation of the DNA-binding activity of SPCH mediated by CRY1 inhibition of the AGB1-SPCH interaction. We propose that the antagonistic regulation of SPCH DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize stomatal density and pattern.

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