Huixue Dong1,2,3, Danping Li1,3, Ruizhen Yang1, Lichao Zhang1, Yunwei Zhang1, Xu Liu1, Xiuying Kong1,*, and Jiaqiang Sun1,*
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu, Sichuan, China
- These authors contributed equally to this work.
Background: For wheat (Triticum aestivum), plant height is a crucial agronomic trait because high plants are prone to lodging (falling over). During the Green Revolution in the 1960s, the unprecedented wheat yield increases were achieved through the introduction of Reduced height (Rht)-B1b and Rht-D1b semi-dwarfing alleles, which confer increased harvest index and improved lodging resistance. Rht-B1b and Rht-D1b alleles produce N-terminal truncated DELLA proteins generated by translational re-initiation, which are stabilized by lacking an intact DELLA motif, leading to reduced plant height. The DELLA proteins are well known as negative regulators of gibberellin signaling in plants. However, the molecular basis of how the Green Revolution proteins Rht-B1b and Rht-D1b act to reduce plant height in wheat remains to be clarified.
Question: How is the stabilized Rht-B1b protein activated or regulated to reduce plant height in wheat?
Findings: We cloned a gain-of-function allele of GSK3 gene through characterization of a dwarf wheat mutant. The GSK3 kinase was shown to interact with and phosphorylate Rht-B1b to promote it to reduce wheat plant height. The phosphorylation by GSK3 may enhance the activity and stability of Rht-B1b. Moreover, GSK3-mediated plant growth repression requires DELLA proteins. Overall, we uncover an activation mechanism for the Green Revolution protein Rht-B1b, which not only needs to be stabilized but also needs to be activated by direct phosphorylation via GSK3 to exert its function in reducing wheat plant height.
Next steps: We plan to generate more wheat mutants with modified plant architecture by CRISPR/Cas9 or EMS-mutagenesis and elucidate the regulatory network of wheat plant architecture, which will provide new insights and elite genes for wheat improvement.
Huixue Dong, Danping Li, Ruizhen Yang, Lichao Zhang, Yunwei Zhang, Xu Liu, Xiuying Kong and Jiaqiang Sun (2023) GSK3 phosphorylates and regulates the Green Revolution protein Rht-B1b to reduce plant height in wheat. Plant Cell. https://doi.org/10.1093/plcell/koad090