Characterization of the mechanisms underlying the tolerance of genotypes of Uva Cão to climate change: A transcriptomic and genomic study

Abstract

Climate change has been influencing viticulture and changing wine profiles in the past years, and effects are expected to get worse. Innovative approaches that explore intravarietal variability to identify genotypes tolerant to abiotic stress have been developed in the past decade, with results already available for some varieties. A variety can be clearly characterized by its unique phenotype, be it its ampelographic characteristics or its physiological behavior, and by its genotype, through molecular markers or genome sequencing.

In the current work, 77 genotypes of the variety Uva Cão, established in an experimental field according to a resolvable row-column design with 6 replicates, were characterized for their level of tolerance to abiotic stress, using expedite measurements of physiological parameters. Linear mixed models were fitted to the data of the traits evaluated, and the empirical best linear unbiased predictors (EBLUPs) of genotypic effects for each trait were obtained as well as the coefficient of genotypic variation (CVG) and broad sense heritability. These genotypes were ranked according to their tolerance to abiotic stress. The group of genotypes with increased tolerance and the group of most sensitive genotypes were sampled for RNAseq and DNAseq analyses. RNA Samples were taken prior to veraison, on conditions of intense environmental stress. These analyses enabled the characterization of the transcriptome of the sensitive and of the tolerant genotypes and the identification of several markers of tolerance. Whole genome sequencing (WGS) is a highly detailed method to identify grapevine varieties but also to differentiate clones within those varieties, as well as to characterize the genetic features that may confer tolerance to stress to the set of tolerant clones.