Abstract: SWEET (sugars will eventually be exported transporters) genes widely present in plants, animals and microorganisms, and form transmembrane channels in the cell membrane or organelle membrane to assist sugar transport across the membrane. Three Arabidopsis SWEET1/2/3 comprise the CladeⅠ subfamily of the SWEET gene family. By expression data analysis, SWEET1 was preferentially expressed in floral organs, SWEET2 was expressed in vegetative growth and reproductive growth, and SWEET3 was expressed in flowers. Although being characterized as active glucose transporters in vitro, their physiological functions were still unclear, probably because of a lack of loss-of-function mutants and functional redundancy. In this study, the targeted mutations in sweet1/2/3 were created by using the CRISPR/Cas9 system, and the sweet1、sweet1/2、sweet3和sweet1/2/3 mutants were identified. All of these mutants did not show obvious phenotypes during vegetative growth, however, interestingly, they displayed significantly shorter siliques than that of wild type (WT). Moreover, the sweet1, sweet1/2, and sweet1/2/3 mutants were more sensitive to glucose, characterized by shorter roots and severely reduced stature under, indicating that SWEET1/2/3 were indispensable components in glucose signaling. Further analysis on the critical genes in glucose signaling pathway found that HXK1, KIN10 and KIN11 did not show any difference of transcriptional and translational expression between WT and the mutants. The results suggested the Arabidopsis SWEET1/2/3 genes played important roles in glucose signaling, especially on regulating siliques development.

Key words: CRISPR/Cas9, Arabidopsis SWEET1/2/3, glucose sensitivity, silique development

摘要： SWEET (sugars will eventually be exported transporters) 基因广泛存在于植物、动物和微生物中，在细胞膜或者细胞器膜形成跨膜孔道，协助糖类物质完成跨膜运输。拟南芥SWEET1/2/3基因属于SWEET基因家族CladeⅠ分支。通过表达谱数据分析发现，SWEET1基因在花器官优先表达，SWEET2基因在营养生长和生殖生长期均有表达，SWEET3基因在花中表达。三个基因在体外鉴定具有葡萄糖转运活性，但由于缺少功能缺失的突变体和功能冗余，它们的生理功能仍不清楚。通过CRISPR/Cas9系统在SWEET1/2/3基因中创建了靶向突变，鉴定获得了sweet1、sweet1/2、sweet3和sweet1/2/3突变体。突变体在营养生长过程中表型与野生型相同，但它们的角果长度显著短于野生型的角果。在高浓度葡萄糖培养基上，sweet1、sweet1/2和sweet1/2/3突变体对葡萄糖敏感，其特征是根更短，高度严重降低，表明 SWEET1/2/3基因在葡萄糖信号中具有功能。对葡萄糖信号通路中关键基因的进一步分析发现，HXK1、KIN10和KIN11在野生型和突变体之间转录和翻译水平没有显著差异。结果表明，拟南芥SWEET1/2/3基因在葡萄糖信号传导和调节角果的发育中起着重要作用。

关键词: CRISPR/Cas9, 拟南芥SWEET1/2/3, 葡萄糖敏感性, 角果发育