Nguyen Cuong X, Paddock Kyle J, Zhang Zhanyuan, Stacey Minviluz G
Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA.
New Phytol. 2021 Jan;229(2):920-934. doi: 10.1111/nph.16928. Epub 2020 Oct 14.
Seed weight is one of the most important agronomic traits in soybean for yield improvement and food production. Several quantitative trait loci (QTLs) associated with the trait have been identified in soybean. However, the genes underlying the QTLs and their functions remain largely unknown. Using forward genetic methods and CRISPR/Cas9 gene editing, we identified and characterized the role of GmKIX8-1 in the control of organ size in soybean. GmKIX8-1 belongs to a family of KIX domain-containing proteins that negatively regulate cell proliferation in plants. Consistent with this predicted function, we found that loss-of-function GmKIX8-1 mutants showed a significant increase in the size of aerial plant organs, such as seeds and leaves. Likewise, the increase in organ size is due to increased cell proliferation, rather than cell expansion, and increased expression of CYCLIN D3;1-10. Lastly, molecular analysis of soybean germplasms harboring the qSw17-1 QTL for the big-seeded phenotype indicated that reduced expression of GmKIX8-1 is the genetic basis of the qSw17-1 phenotype.
种子重量是大豆中用于提高产量和粮食生产的最重要农艺性状之一。大豆中已鉴定出几个与该性状相关的数量性状位点（QTL）。然而，这些QTL的潜在基因及其功能仍大多未知。利用正向遗传学方法和CRISPR/Cas9基因编辑技术，我们鉴定并表征了GmKIX8-1在控制大豆器官大小中的作用。GmKIX8-1属于含KIX结构域的蛋白质家族，该家族在植物中负调控细胞增殖。与这一预测功能一致，我们发现功能缺失的GmKIX8-1突变体地上植物器官（如种子和叶片）的大小显著增加。同样，器官大小的增加是由于细胞增殖增加，而非细胞扩张增加，以及细胞周期蛋白D3;1-10的表达增加。最后，对具有大粒种子表型的qSw17-1 QTL的大豆种质进行分子分析表明，GmKIX8-1表达降低是qSw17-1表型的遗传基础。
