Introgression of Muscadinia rotundifolia Resistance Genes into Grapevine

Since the XIXth century, European grapevine, Vitis vinifera, have been threatened by several diseases introduced in Europe from North America. Muscadinia rotundifolia, a related species native to the southern United States of America, is a major source of resistance to grapevine diseases, widely used in the French breeding programs. Backcross-based introgression was used to transfer resistance factors from M.rotundifolia into cultivated backgrounds while eliminating the unwanted cultural traits and off-flavours. However, crosses between both species display a low success rate, most of the hybrids being sterile and phenotypic abnormalities being observed in the offspring. Within this context, it is essential to identify M. rotundifolia traits important to discard during the introgression process and the genomic features that impede crosses between the two species.

To address these questions, we have, first, compared the organisation of the M. rotundifolia and V. vinifera genomes. A high-density genetic linkage map was established mainly by Genotyping-by-Sequencing thanks to two mapping populations generated by pseudo-backcrosses between, on one hand, M. rotundifolia, and on the other hand, several V. vinifera cultivars. Parental and consensus maps were obtained showing a high level of macrosynteny between the two species.

Morphological and developmental traits and metabolites were analysed in a collection of accessions of M. rotundifolia and V. vinifera in order to identify which traits are specific to M. rotundifolia. Their genetic determinism was analysed in the mapping populations and their transmission into advanced pseudo-backcross populations was studied.