Exploring Genomic Differences between a Pair of Vitis vinifera Clones Using WGS Data: A Preliminary Study

Abstract

The differentiation of clones within grape cultivars, specifically Vitis vinifera, has significant potential for the wine industry. This differentiation involves associating morphological features or a genetic signature with a particular cultivar clone, which is a challenging task. It has been difficult to experimentally find genetic signatures that differentiate a pair of clones, despite evidence suggesting that genomic differences exist. Are there genetic or genomic differences in a pair of clones? If so, where are the variations in the genome? Are there variations in protein coding genes? We addressed these questions by performing a bioinformatic analysis to identify genetic differences between certified clones of the same cultivar. Utilising genome sequencing data from tissue samples, we identified genomic positions differing between the clones and their cultivar reference genome, meeting the filtering criteria. Applying this approach to the Carménère and Merlot clones resulted in 5718 and 5218 variations, respectively, that differentiated the clones. Visual validation of 50 variations per cultivar revealed that 12% of these variations were located in the Merlot genes, while 32% were found in the Carménère genes. We estimated between 600 and 1000 variations per cultivar that could be validated by visual inspection. Despite the presence of these variations within genes, none was found to have a disruptive effect on protein function. By comparing our results with those of previous studies, we discuss issues pertaining to clone differentiation. In conclusion, there are genomic variations in pairs of clones that allow for their differentiation, though the variations are not directly related to the phenotype.