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 result indicates 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.

中文翻译：

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VvSUPERMAN样基因在Vitis vinifera L. cv的双小花和三小花小花之间差异表达。“香妃”及其异源表达减少了番茄中的心皮数。

多羧酸盐的果实比单或双羧酸盐的果实更大并且产生更多的种子，从而增强了植物的繁殖能力。为了鉴定不同心皮类型的小花之间的表型和分子差异，我们研究了葡萄（Vitis vinifera）品种“香妃”中心皮的形成和融合，该品种产生了高比例的多心皮果。我们还确定功能VvSUPERMAN样（VvSUP类），并探讨其关系VvWUS（VvWUSCHEL）和VvAG1（VvAGAMOUS），这与心皮原基的形成有关。我们发现双心形和三心形卵巢之间的心皮形成和融合在很大程度上是一致的，这两者都涉及先天性融合。相反，这些子房类型之间的差异是由心皮原基数量和位置的变化引起的。表达VvSUP样的转基因番茄（Solanum lycopersicum）植物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样在双羧酸盐中比在三羧酸盐“香妃”小花中表达更高。萤光素酶报告基因检测表明VvSUP样抑制VvAG1和VvWUS的表达通过直接与其启动子结合，VvWUS通过直接与其启动子结合来促进VvAG1表达。类VvSUP抑制了VvWUS和VvAG1之间的反馈信号。总之，这些结果表明，VvSUP样通过抑制VvAG1和VvWUS的表达来负调节心皮的数量。