Genetic Diversity and Population Structure in a Vitis spp. Core Collection Investigated by SNP Markers

Single nucleotide polymorphism (SNP) genotyping arrays are powerful tools to measure the level of genetic polymorphism within a population. The coming of next-generation sequencing technologies led to identifying thousands and millions of SNP loci useful in assessing the genetic diversity. The Vitis genotyping array, containing 18k SNP loci, has been developed and used to detect genetic diversity of Vitis vinifera germplasm. So far, this array was not validated on non-vinifera genotypes used as grapevine rootstocks. In this work, a core collection of 70 grapevine rootstocks, composed of individuals belonging to Vitis species not commonly used in the breeding programs, was genotyped using the 18k SNP genotyping array. SNP results were compared to the established SSR (Simple Sequence Repeat) markers in terms of heterozygosity and genetic structure of the core collection. Genotyping array has proved to be a valuable tool for genotyping of grapevine rootstocks, with more than 90% of SNPs successfully amplified. Structure analysis detected a high degree of admixed genotypes, supported by the complex genetic background of non-vinifera germplasm. Moreover, SNPs clearly differentiated non-vinifera and vinifera germplasm. These results represent a first step in studying the genetic diversity of non-conventional breeding material that will be used to select rootstocks with high tolerance to limiting environmental conditions.