Umar Shahbaz, University of Montpellier/BIOPOLIS-CIBIO
July 15, 2026 | 10h00 | CIBIO’s Auditorium
Grapevine (Vitis vinifera) is a perennial fruit crop of major economic importance whose reproductive biology is governed by a complex sex determination region (SDR). Wild V. vinifera ssp. sylvestris is dioecious, while the vast majority of cultivated varieties are hermaphroditic, a transition that facilitated domestication approximately 8,000 years ago. This shift is controlled by a ~200 kb sex-determining region (SDR) on chromosome 2, which harbors distinct M-, H-, and F-haplotypes carrying 15–20 genes. Promising candidates include VviINP1 (associated with male sterility), VviYABBY3(linked to female sterility), VviAPRT3, and other sex related loci, whose spatio temporal expression patterns will be analyzed during floral development. To functionally dissect this region, this project uses the microvine (MiV), a dwarf model of grapevine carrying a loss of function mutation in the VviGAI1 gene of the gibberellin signaling pathway. This mutation confers a compact architecture, shortened internodes, and undergo several flowering cycles per year. These traits enable multiple generations per year under controlled conditions, making the microvine an ideal platform for rapid genetic and functional studies. The main objective is to generate and characterise microvine (MiV) segregating populations that express the three flower sexes (male, female, and hermaphrodite). We will combine transcriptomic profiling (RNA-seq and RT-qPCR) and spatial gene expression analysis (in situ hybridization) to establish the spatio temporal expression patterns of SDR candidate genes during key stages of flower development. Functional validation will be achieved through targeted genome editing and ectopic expression of candidate genes (including VviINP1, VviYABBY3 and VviAPRT3) in hermaphroditic microvine lines using Golden Braid based cloning and CRISPR-based approaches. Resulting edited lines will undergo detailed phenotyping at vegetative (growth, photosynthesis) and reproductive levels (flower morphology, stamen/carpel development, pollen viability). Through microvine based genome editing, this study will establish direct links between specific SDR genes and sexual phenotypes, providing fundamental insights into stamen and carpel development. At the same time, it will deliver practical tools such as haplotype markers for early sex prediction and the development of fertility-optimized cultivars. Overall, this microvine-based approach effectively bridges basic reproductive biology with applied grapevine breeding.
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