Cgr1, a ripe rot resistance QTL in Vitis amurensis ‘Shuang Hong’ grapevine

Ripe rot is a serious grapevine disease in Vitis L. and Muscadinia (Planch.) Small. However, resistance to this disease has been reported in some oriental Vitis species. To identify resistance-related Quantitative Trait Loci (QTLs) from the Chinese grape species V. amurensis, an F(1) population of V. vinifera ‘Cabernet Sauvignon’ × V. amurensis ‘Shuang Hong’ was used to map the ripe rot resistance loci expected in ‘Shuang Hong’ grape. A total of 7598 single nucleotide polymorphisms (SNPs) between the parents were identified in our previous study, and 934 SNPs were selected for genetic map construction. These SNPs are distributed across the 19 chromosomes covering a total of 1665.31 cM in length, with an average of 1.81 cM between markers. Ripe rot resistance phenotypes among the hybrids were evaluated in vitro using excised leaves for three consecutive years from 2016 to 2018; a continuous variation was found among the F(1) hybrids, and the Pearson correlation coefficients of the phenotypes scored in all three years were significant at the 0.01 level. Notably, the first QTL reported for resistance to grape ripe rot disease, named Cgr1, was identified on chromosome 14 of ‘Shuang Hong’ grapevine. Cgr1 could explain up to 19.90% of the phenotypic variance. In addition, a SNP named ‘np19345’ was identified as a molecular marker closely linked to the peak of Cgr1 and has the potential to be developed as a marker for the Cgr1 resistance haplotype.