College of Horticulture, China Agriculture University, Beijing 100094, China.
Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany.
Plant Cell Physiol. 2020 Oct 1;61(10):1760-1774. doi: 10.1093/pcp/pcaa103.
Multicarpellate fruits are larger and produce more seeds than mono- or bicarpellate fruits, enhancing the reproductive capacity of the plant. To identify the phenotypic and molecular differences among florets of different carpel types, we studied carpel formation and fusion in the grapevine (Vitis vinifera) cultivar 'Xiangfei', which produces a high proportion of multicarpellate fruit. We also determined the function of VvSUPERMAN-like (VvSUP-like) and explored its relationship with VvWUS (VvWUSCHEL) and VvAG1 (VvAGAMOUS), which is related to the formation of carpel primordia. We showed that carpel formation and fusion were largely consistent between bicarpellate and tricarpellate ovaries, which both involve congenital fusion; rather, the differences between these ovary types arose from variation in carpel primordia number and location. Transgenic tomato (Solanum lycopersicum) plants expressing VvSUP-like produced significantly fewer carpels and other floral organs than the wild type. Moreover, transcriptome sequencing results indicate that VvSUP-like was more highly expressed in bicarpellate than in tricarpellate 'Xiangfei' florets. Luciferase reporter assays indicated that VvSUP-like inhibits the expression of VvAG1 and VvWUS by directly binding to their promoters, and VvWUS promotes VvAG1 expression by directly binding to its promoter. VvSUP-like inhibits the feedback signaling between VvWUS and VvAG1. Together, these results suggest that VvSUP-like negatively regulates the number of carpels that develop by inhibiting VvAG1 and VvWUS expression.
多心皮果实比单心皮或双心皮果实更大，产生的种子也更多，从而提高了植物的繁殖能力。为了鉴定不同心皮类型小花之间的表型和分子差异，我们研究了葡萄（Vitis vinifera）品种“湘妃”的心皮形成和融合，该品种产生了很高比例的多心皮果实。我们还确定了 VvSUPERMAN-like（VvSUP-like）的功能，并探讨了它与 VvWUS（VvWUSCHEL）和 VvAG1（VvAGAMOUS）的关系，VvWUS 和 VvAG1 与心皮原基的形成有关。我们表明，双心皮和三心皮子房的心皮形成和融合在很大程度上是一致的，都涉及先天性融合；相反，这些子房类型之间的差异来自心皮原基数量和位置的变化。表达 VvSUP-like 的转基因番茄（Solanum lycopersicum）植株产生的心皮和其他花器官明显少于野生型。此外，转录组测序结果表明，VvSUP-like 在双心皮“湘妃”小花中的表达高于三心皮。荧光素酶报告基因检测结果表明，VvSUP-like 通过直接结合其启动子抑制 VvAG1 和 VvWUS 的表达，而 VvWUS 通过直接结合其启动子促进 VvAG1 的表达。VvSUP-like 抑制 VvWUS 和 VvAG1 之间的反馈信号。总之，这些结果表明，VvSUP-like 通过抑制 VvAG1 和 VvWUS 的表达，负调控发育的心皮数量。
