Improving cold tolerance in rice: How wrky53 mutants give cold stress the boot
Background: Rice (Oryza sativa L.) is a staple food for over half of the global population. Cold stress at the booting stage leads to serious yield losses and has become a major limiting factor for rice production in regions of higher altitude and latitude. Therefore, isolating cold tolerance genes to facilitate breeding cultivars with higher cold tolerance at the booting stage (CTB) remains an urgent concern. Rice cold tolerance is a complex trait that is controlled by multiple loci. Due to the difficulties in identifying CTB phenotypes, only a few genes regulating CTB have been functionally characterized thus far.
Question: We aimed to characterize a CTB-related gene, WRKY53, and investigate its underlying mechanism, then use it to breed rice varieties with greater CTB.
Findings: We identified the cold-induced WRKY transcription factor WRKY53 and found that WRKY53 negatively regulates rice CTB. WRKY53 fine-tuning gibberellic acid (GA) levels in anthers via directly transcriptionally repressing GA biosynthesis genes in anthers. Moreover, we demonstrate that the possible mechanism of GA regulating male fertility in which a DELLA protein interacts with two critical transcription factors for tapetum development, and GA promotes the degradation of this DELLA protein, allowing the transcription factors to activate downstream genes. Importantly, knocking out WRKY53 in diverse varieties increases cold tolerance without a yield penalty, leading to a higher yield in rice subjected to cold stress. Therefore, WRKY53 is a valuable target for cold-tolerance breeding.
Next steps: WRKY53 negatively regulates resistance to Xanthomonas oryzae pv. oryzae sheath blight, striped stem borer, and CTB in rice. We are interested in evaluating the practical value of wrky53 mutants by assessing their yield under multiple conditions, including pathogen infection, insect pests, and low temperature or other stresses in the field.
Reference:
Jiaqi Tang, Xiaojie Tian, Enyang Mei, Mingliang He, Junwen Gao, Jun Yu, Min Xu, Jiali Liu, Lu Song, Xiufeng Li, Zhenyu Wang , Qingjie Guan, Zhigang Zhao, Chunming Wang, Qingyun Bu (2022) WRKY53 negatively regulates rice cold tolerance at the booting stage by fine-tuning anther gibberellin levels. Plant Cell. https://doi.org/10.1093/plcell/koac253
