Tao Yongsheng, Zhou Mingting, Zhang Daxiao, Feng Liqing, Tao Anyan, Zhang Xuehai
State Key Laboratory of North China Crop Improvement and Regulation, North China Key Laboratory for Crop Germplasm Resources of the Education Ministry, College of Agronomy, Hebei Agricultural University, Baoding, 071001, China.
College of Agriculture, Northeast Agricultural University, Harbin, 150030, China.
Theor Appl Genet. 2025 Aug 5;138(8):198. doi: 10.1007/s00122-025-04992-y.
Map-based cloning of ZmSS5. ZmSS5 pathway was constructed and validated. The 'ZmSS5 hypothesis' was proposed. Kernel weight (KW) is an important determinant of maize yield. Despite the identification of numerous quantitative trait loci (QTL) for KW, research into the cloning and molecular regulation of these loci is limited, limiting progress in genetic improvement and molecular breeding for KW. In this study, linkage analysis by chromosomal segment introgression lines, marker development, high-throughput sequencing, amplification and sequence alignment of genome and cDNA, analysis of gene expression and variable splicing, detection of sucrose content and starch synthase activity, the AtSS5 T-DNA insertion mutant and the ZmSS5 EMS mutant were used, and Zm00001d051976 was finally confirmed as the functional gene of the QTL for KW (qKW4a) encoding starch synthase 5 (ZmSS5). Based on RNA-seq from two early stages of grain development, a weighted correlation network analysis was constructed to identify and verify the ZmSS5 pathway, which regulates starch metabolism and KW formation through C/N balance. We also proposed the 'ZmSS5 hypothesis', which suggests that proliferation of starch granules and an increase in ZmSS5 levels are accompanied by cell proliferation, which affects starch unit storage and KW formation by C/N balance. This will provide new ideas for the molecular regulation of KW formation in maize, as well as gene and marker resources for KW molecular breeding.
基于图谱克隆ZmSS5。构建并验证了ZmSS5通路。提出了“ZmSS5假说”。粒重（KW）是玉米产量的一个重要决定因素。尽管已鉴定出众多与KW相关的数量性状位点（QTL），但对这些位点的克隆及分子调控研究有限，限制了KW遗传改良和分子育种的进展。在本研究中，利用染色体片段渗入系进行连锁分析、标记开发、高通量测序、基因组和cDNA的扩增及序列比对、基因表达和可变剪接分析、蔗糖含量和淀粉合酶活性检测、AtSS5 T-DNA插入突变体和ZmSS5 EMS突变体，最终确定Zm00001d051976为KW的QTL（qKW4a）的功能基因，该基因编码淀粉合酶5（ZmSS5）。基于籽粒发育两个早期阶段的RNA测序，构建了加权相关网络分析以鉴定和验证ZmSS5通路，该通路通过碳/氮平衡调节淀粉代谢和KW形成。我们还提出了“ZmSS5假说”，即淀粉颗粒的增殖和ZmSS5水平的增加伴随着细胞增殖，这通过碳/氮平衡影响淀粉单位储存和KW形成。这将为玉米KW形成的分子调控提供新思路，以及为KW分子育种提供基因和标记资源。
