State Key Laboratory of Maize Bio-breeding, Beijing Innovation Center for Crop Seed Technology (MOA), College of Agronomy and Biotechnology, China Agricultural University, Beijing, China.
Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.
Plant Biotechnol J. 2024 Sep;22(9):2472-2487. doi: 10.1111/pbi.14362. Epub 2024 May 18.
Seed vigour, including rapid, uniform germination and robust seedling establishment under various field conditions, is becoming an increasingly essential agronomic trait for achieving high yield in crops. However, little is known about this important seed quality trait. In this study, we performed a genome-wide association study to identify a key transcription factor ZmRap2.7, which regulates seed vigour through transcriptionally repressing expressions of three ABA signalling genes ZmPYL3, ZmPP2C and ZmABI5 and two phosphatidylethanolamine-binding genes ZCN9 and ZCN10. In addition, ZCN9 and ZCN10 proteins could interact with ZmPYL3, ZmPP2C and ZmABI5 proteins, and loss-of-function of ZmRap2.7 and overexpression of ZCN9 and ZCN10 reduced ABA sensitivity and seed vigour, suggesting a complex regulatory network for regulation of ABA signalling mediated seed vigour. Finally, we showed that four SNPs in ZmRap2.7 coding region influenced its transcriptionally binding activity to the downstream gene promoters. Together with previously identified functional variants within and surrounding ZmRap2.7, we concluded that the distinct allelic variations of ZmRap2.7 were obtained independently during maize domestication and improvement, and responded separately for the diversities of seed vigour, flowering time and brace root development. These results provide novel genes, a new regulatory network and an evolutional mechanism for understanding the molecular mechanism of seed vigour.
种子活力，包括在各种田间条件下快速、均匀的萌发和健壮的幼苗建立，正在成为实现作物高产的一个越来越重要的农艺性状。然而，人们对这个重要的种子质量性状知之甚少。在这项研究中，我们进行了全基因组关联研究，鉴定了一个关键的转录因子 ZmRap2.7，它通过转录抑制三个 ABA 信号基因 ZmPYL3、ZmPP2C 和 ZmABI5 和两个磷脂酰乙醇胺结合基因 ZCN9 和 ZCN10 的表达来调节种子活力。此外，ZCN9 和 ZCN10 蛋白可以与 ZmPYL3、ZmPP2C 和 ZmABI5 蛋白相互作用，ZmRap2.7 的功能丧失和 ZCN9 和 ZCN10 的过表达降低了 ABA 敏感性和种子活力，表明 ABA 信号介导的种子活力的调控存在一个复杂的调控网络。最后，我们表明，ZmRap2.7 编码区的四个 SNP 影响其对下游基因启动子的转录结合活性。结合之前在 ZmRap2.7 内部和周围鉴定的功能变体，我们得出结论，ZmRap2.7 的不同等位基因变异是在玉米驯化和改良过程中独立获得的，分别响应种子活力、开花时间和支根发育的多样性。这些结果为理解种子活力的分子机制提供了新的基因、新的调控网络和进化机制。
