The correlation between VvYABBY5 expression and the ontogeny of tricarpellate fruit in ‘Xiangfei’ grapevine (Vitis vinifera)

Abstract

ABSTRACTCarpel morphogenesis is crucial for seed development, and fruit size and quality, and carpel number is one measure of the level of plant evolution. A comparative study of morphogenesis and gene modulation was initiated to study the ontogeny of bi- and tricarpellate fruits. In our study, ‘Xiangfei’ grapevine (Vitis vinifera) was used as the plant material because of its high tricarpellate occurrence. Results showed that congenital fusion was the main pathway for tricarpellate ovary ontogeny. There were three ventral sutures on tricarpellate fruits in the period of flowering, and this feature was absent from bicarpellate fruits. From 20 to 40 days after flowering (DAF), the growth rate of tricarpellate fruits was greater than that of bicarpellate fruits. Four VvYABBY genes were identified from the grapevine genome by BLAST searches using the sequence of tomato SlFASCIATED (SlFAS is a protein that negatively regulates locule number). Real-time PCR determined the transcript levels of the VvYABBY genes in bicarpellate and tricarpellate ovaries. Only the transcript level of VvYAB5 in tricarpellate ovaries was lower than that in bicarpellate ovaries in different developmental periods. In situ analysis showed that VvYAB5 transcripts were detected in carpel primordia and placental tissue. Taken together, a tentative inference is that the VvYAB5 gene might play a role in tricarpellate fruit formation.