Su Wenxin, Huang Jing, Wang Bo, Liu Yaqi, Chen Yijia, Li Yingyin, Yang Naiying, Wang Kaiqi, Xu Xiaofeng
Shanghai Collaborative Innovation Center of Plant Germplasm Resources Development, College of Life Sciences, Shanghai Normal University, Shanghai, China.
College of Biological and Environmental Engineering, Jingdezhen University, Jiangxi, China.
Plant Mol Biol. 2025 Jan 17;115(1):18. doi: 10.1007/s11103-024-01549-3.
The accurate callose deposition plays important roles in pollen wall formation and pollen fertility. As a direct target of miRNA160, ARF17 participate in the formation of the callose wall. However, the impact of ARF17 misexpression in microsporocytes on callose wall formation and pollen fertility remains unknown. Here, the SDS promoter, which is capable of specifically driving gene expression in microsporocytes, was employed to drive the expression of 5mARF17. The pSDS:5mARF17#3 transgenic line were male sterile. TEM revealed that sporopollenin substance was embedded in a thicker callose layer, which resulted in the complete loss of exine structure and pollen abortion in the pSDS:5mARF17#3 line. Consistently, RT-qPCR revealed an increase in the expression of several Cals genes in pSDS:5mARF17#3. EMSA assay demonstrated that ARF17 could bind to the promoter of Cals4 gene, which further suggest that ARF17 could regulate several Cals genes expression. It is notable that the expression of several exine formation-related genes increased significantly in pSDS:5mARF17#3. In conclusion, our findings highlight that the regulation of miRNA160-ARF17 in microsporocytes modulates the thickness of the callose wall, which is crucial for pollen exine formation and intercellular communication.
精确的胼胝质沉积在花粉壁形成和花粉育性中发挥着重要作用。作为miRNA160的直接靶标，ARF17参与胼胝质壁的形成。然而，ARF17在小孢子母细胞中的错误表达对胼胝质壁形成和花粉育性的影响仍不清楚。在此，利用能够在小孢子母细胞中特异性驱动基因表达的SDS启动子来驱动5mARF17的表达。pSDS:5mARF17#3转基因系雄性不育。透射电镜显示孢粉素物质包埋在较厚的胼胝质层中，这导致pSDS:5mARF17#3系外壁结构完全丧失和花粉败育。一致地，RT-qPCR显示pSDS:5mARF17#3中几个Cals基因的表达增加。电泳迁移率变动分析表明ARF17可以结合Cals4基因的启动子，这进一步表明ARF17可以调控几个Cals基因的表达。值得注意的是，在pSDS:5mARF17#3中几个外壁形成相关基因的表达显著增加。总之，我们的研究结果突出表明，小孢子母细胞中miRNA160-ARF17的调控调节了胼胝质壁的厚度，这对花粉外壁形成和细胞间通讯至关重要。
