Polymorphisms in VvPel associate with variation in berry texture and bunch size in the grapevine

Abstract

[Background and Aims] The identification of the genes involved in traits of interest is one of the main aims of current plant genetic studies. Although berry texture is a quality trait of great importance in table grapes, no quantitative trait loci or related gene has been described for this trait so far.

[Methods and Results] In this work, the gene VvPel, which codes for a pectate lyase in the grapevine, was selected as a candidate gene for an association study. This gene was sequenced in a core collection of 96 table grape accessions, which was also characterised for several bunch and berry morphological traits, including diverse texture parameters measured by means of a texture meter. The population structure, the nucleotide and haplotype diversity, the protein structure, the existence of selection, and the linkage disequilibrium (LD) were evaluated. Thirty-two single nucleotide polymorphisms (SNPs) and 15 haplotypes were identified in the VvPel sequence, and LD was low enough to provide a high-resolution power. Some of the polymorphisms associated significantly with texture parameters and with bunch size, explaining part of the variation found for those traits.

[Conclusions] Among the polymorphisms found in the gene VvPel, S1027 and S405/S441 in relation to berry texture, and S48/S1030 in relation to bunch size, are the most promising and would need to be investigated further as putative causal polymorphisms or markers for the respective traits.

[Significance of the Study] The present work is the first genetic study on berry texture in the grapevine, and constitutes a starting point for a deeper understanding of the genetic basis of the natural variation for berry texture and bunch size. © 2013 Australian Society of Viticulture and Oenology Inc.