Corinto Nero raw sequence reads
Both parthenocarpy and stenospermocarpy lead to seedless grapes. Only parthenocarpy, which is rather rare, generates berries with a complete absence of seed tissues. Stenospermocarpy, which is instead more common, produces berries with seed traces because seed development is promoted by embryo formation and then arrested by its abortion. Commercially, stenospermocarpic varieties are the main source of seedless table grapes. Parthenocarpy is the putative cause of seedlessness in Corinto Nero, a bud sport of the seeded winegrape Sangiovese. In our previous studies, embryo sac abnormalities arising from meiotic disorders were accompanied by transcriptional changes in gene functions linked to gametophyte development and ovule fertilization. Here, with the aim of elucidating the root cause of parthenocarpy in Corinto Nero, comparative histological and genomic analyses were performed. Histologically, Corinto Nero showed abnormalities in megasporogenesis and the arrest of the female gametophyte development very early during the megagametogenesis, compared to seeded Sangiovese. Genetically, Corinto Nero showed putative private mutations in candidate genes with functions related to cell cycle, meiosis and mitosis, compared to another ten Sangiovese bud sports, which differed phenotypically from one another and from Corinto Nero for diverse traits but they all were seeded. This work provided a list of candidate genes wjth somatic mutations in Corinto Nero that possibly impair sporogenesis and gametogenesis, preventing seed development. Sangiovese has a genetic predisposition to develop ovary disorders, and to forcibly set fruit in absence of pollination, which may have been turned into full expression of parthenocarpy in Corinto Nero by further mutations.