A transcriptional hub integrates multiple hormone signaling pathways in rice

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Duan et al. explore the functions of OsSHI1 in rice development.

https://doi.org/10.1093/plcell/koad130

Erchao Duan

State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University

Background: Plant growth and development are affected by various internal and external signals during their entire life cycle. To improve their chances of surviving and reproducing, plants have evolved complex ways to coordinate their growth and stress responses via integrating hormone signaling pathways. Therefore, revealing the molecular mechanisms integrating various hormone signaling pathways is not only a fundamental biological question, but also holds great promise for molecular breeding of high-yielding and stress-resilient crops in face of climate change and increasing human population.

Questions: The multifaceted hormone-related defects of the rice short internodes1 (shi1) mutant give us a clue that the OsSHI1 gene might participate in regulating multiple hormone signaling pathways. Therefore, we asked whether and how different hormone signaling pathways are integrated by OsSHI1 at the transcriptional level during rice development.

Findings: We found that the shi1 mutant exhibits many hormone-related morphological variations, such as auxin and brassinosteroid (BR)-regulated plant development as well as abscisic acid (ABA)-mediated stress tolerance. Further functional analysis revealed that several upstream transcription factors of auxin, ABA and BR pathways bind to the promoter region of OsSHI1 to activate or inhibit its transcription. OsSHI1 protein then directly regulates several auxin and BR biosynthesis genes, thus integrating the biosynthesis of auxin and BR with ABA signal transduction to coordinate plant growth and stress adaptation. In addition, OsSHI1 also negatively regulates its own expression. These findings demonstrate that OsSHI1 is a key transcriptional hub for the integration of multiple hormone signaling pathways.

Next steps: SHI family members are essential regulators of plant development. Therefore, it is important to identify and explore their functions in other hormone pathways or stresses to fully understand the biological functions of SHI transcription factors in coordinating plant development and stress adaptation in future studies.

Reference:

Erchao Duan, Qibing Lin, Yihua Wang, Yulong Ren, Huan Xu, Yuanyan Zhang, Yunlong Wang, Xuan Teng, Hui Dong, Yupeng Wang, Xiaokang Jiang, Xiaoli Chen, Jie Lei, Hang Yang, Rongbo Chen, Ling Jiang, Haiyang Wang, and Jianmin Wan. (2023). The transcriptional hub SHORT INTERNODES1 integrates hormone signals to orchestrate rice growth and development. https://doi.org/10.1093/plcell/koad130