The VvSUPERMAN-like Gene Is Differentially Expressed between Bicarpellate and Tricarpellate Florets of Vitis vinifera L. Cv. ‘Xiangfei’ and Its Heterologous Expression Reduces Carpel Number in Tomato

Abstract

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.

MADS-Box Protein Complex VvAG2, VvSEP3 and VvAGL11 Regulates the Formation of Ovules in Vitis vinifera L. cv. ‘Xiangfei’

“…The prepared paraffin sections were observed and photographed using an Olympus CX31 microscope (Olympus Corporation, Tokyo, Japan). The processes of dehydration and transparency were carried out according to the method described by Liang et al [ 18 ].…”

“…The transgenic plants were cultured in an artificial climate incubator HPG-280 HX (HDL, Changzhou City, China) with the 16 h light/8 h dark photoperiod. The transgenic methods were described as Liang et al [ 18 ]. The wild-type Micro-Tom tomato was used as the negative control for the tomato transformation.…”

“…Most varieties of grape have two carpels and four ovules [ 16 , 17 ]. However, a few varieties developed multi-carpel variation during evolution [ 18 ], and the number of ovules increases correspondingly. In past decades, this topic has been deeply studied and verified in the model plant tomato: increasing the number of carpels helps to greatly increase the tomato fruit size during fruit domestication [ 19 , 20 ].…”

Evaluation of the Possible Contribution of Various Regulatory Genes to Determination of Carpel Number as a Potential Mechanism for Optimal Agricultural Yield

“…Gene SUPERMAN ( SUP ) is a negative repressor of WUS . In grapes ( Vitis vinifera , Vitaceae), multicarpellate berries develop in plants with reduced expression of VvSUP-like [ 55 ]. It was confirmed that VvSUP-like prevents the expression of grape orthologues of SUP targets VvAG1 and VvWUS [ 55 ].…”

“…In grapes ( Vitis vinifera , Vitaceae), multicarpellate berries develop in plants with reduced expression of VvSUP-like [ 55 ]. It was confirmed that VvSUP-like prevents the expression of grape orthologues of SUP targets VvAG1 and VvWUS [ 55 ]. As tri- and tetracarpellate berries are larger, this feature is of agricultural value.…”