Gong Junming, Sun Shichao, Zhu Qian-Hao, Qin Jianghong, Yang Yonglin, Zheng Zhihong, Cheng Shuaishuai, Sun Jie
Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi, Xinjiang, China.
CSIRO Agriculture and Food, GPO Box 1700, Canberra, 2601, Australia.
Plant Physiol Biochem. 2024 Mar;208:108484. doi: 10.1016/j.plaphy.2024.108484. Epub 2024 Mar 2.
Flavonoids have been shown to play an essential role in plant growth and fertility. 4-Coumarate CoA ligase (4CL) is one of the indispensable enzymes involved in the biosynthesis of flavonoids. However, the role of 4CL and flavonoids in impact on cotton fertility is still unknown. In this study, on the basis of identification of an additional Gh4CL gene, Gh4CL20A, by using an updated G. hirsutum genome, we found that Gh4CL20A and its homologous Gh4CL20 were preferentially expressed in petals and stamens. The petals of the loss-of-function Gh4CL20/Gh4CL20A mutant generated by CRISPR/Cas9 gene editing remained white until wilting. Notably, the mutant showed indehiscent anthers, reduced number of pollen grains and pollen viability, leading to male sterility. Histological analysis revealed that abnormal degradation of anther tapetum at the tetrad stage and abnormal pollen grain development at the mature stage caused male sterility of the gene editing mutant. Analysis of the anther transcriptome identified a total of 10574 and 11962 genes up- and down-regulated in the mutant, respectively, compared to the wild-type. GO, KEGG, and WGCNA analyses linked the abnormality of the mutant anthers to the defective flavonoid biosynthetic pathway, leading to decreased activity of 4CL and chalcone isomerase (CHI) and reduced accumulation of flavonoids in the mutant. These results imply a role of Gh4CL20/Gh4CL20A in assuring proper development of cotton anthers by regulating flavonoid metabolism. This study elucidates a molecular mechanism underlying cotton anther development and provides candidate genes for creating cotton male sterile germplasm that has the potential to be used in production of hybrid seeds.
黄酮类化合物已被证明在植物生长和育性中发挥着重要作用。4-香豆酸辅酶A连接酶（4CL）是黄酮类化合物生物合成中不可或缺的酶之一。然而，4CL和黄酮类化合物对棉花育性的影响作用仍不清楚。在本研究中，通过使用更新的陆地棉基因组鉴定出一个额外的Gh4CL基因Gh4CL20A，我们发现Gh4CL20A及其同源基因Gh4CL20在花瓣和雄蕊中优先表达。通过CRISPR/Cas9基因编辑产生的功能缺失型Gh4CL20/Gh4CL20A突变体的花瓣直到枯萎仍为白色。值得注意的是，该突变体表现出花药不开裂、花粉粒数量减少和花粉活力降低，导致雄性不育。组织学分析表明，四分体时期花药绒毡层的异常降解和成熟时期花粉粒的异常发育导致了基因编辑突变体的雄性不育。花药转录组分析确定，与野生型相比，突变体中分别有10574个和11962个基因上调和下调。GO、KEGG和WGCNA分析将突变体花药的异常与有缺陷的黄酮类生物合成途径联系起来，导致突变体中4CL和查尔酮异构酶（CHI）的活性降低以及黄酮类化合物的积累减少。这些结果表明Gh4CL20/Gh4CL20A通过调节黄酮类代谢在确保棉花花药正常发育中发挥作用。本研究阐明了棉花花药发育的分子机制，并为创制具有杂交种子生产潜力的棉花雄性不育种质提供了候选基因。
