Clonal propagation history shapes the intra-cultivar genetic diversity in Malbec grapevines

Abstract

Grapevine (Vitis vinifera L.) cultivars are clonally propagated to preserve their varietal 26 attributes. However, novel genetic variation still accumulates due to somatic mutations. Aiming 27 to study the potential impact of clonal propagation history on grapevines intra-cultivar genetic 28 diversity, we have focused on ‘Malbec’. This cultivar is appreciated for red wines elaboration, 29 it was originated in Southwestern France and introduced into Argentina during the 1850s. Here, 30 we generated whole-genome resequencing data for four ‘Malbec’ clones with different 31 historical backgrounds. A stringent variant calling procedure was established to identify reliable 32 clonal polymorphisms, additionally corroborated by Sanger sequencing. This analysis retrieved 33 941 single nucleotide variants (SNVs), occurring among the analyzed clones. Based on a set of 34 validated SNVs, a genotyping experiment was custom-designed to survey ‘Malbec’ genetic 35 diversity. We successfully genotyped 214 samples and identified 14 different clonal genotypes, 36 that clustered into two genetically divergent groups. Group-Ar was driven by clones with a long 37 history of clonal propagation in Argentina, while Group-Fr was driven by clones that have 38 longer remained in Europe. Findings show the ability of such approaches for clonal genotypes 39 identification in grapevines. In particular, we provide evidence on how human actions may have 40 shaped ‘Malbec’ extant genetic diversity pattern.