Unravelling the genetic determinants of anthocyanin and polyphenol content in grapevines integrating genome wide association studies and metabolomic profiling

Abstract

The quality and productivity of grapevines are highly dependent on environmental factors. Climate change is altering grapevinephysiology and wine production conditions, thus, winegrowers need to adapt to maintain optimal production and wine quality. Flavonoids and other phenolic compounds such anthocyanins and flavonols constitute critical determinants of wine quality, affecting color, stability, and sensory profile of the wine. Our goal is to determine the genetic basis of sensory characteristics by integrating genome-wide association studies (GWAS) and comparative metabolite profiling. To address this issue, a diverse panel of 109 grapevine individuals, including varieties of different genetic backgrounds and segregant lines from the breeding program of the Instituto de Investigaciones Agropecuarias (INIA-La Platina), was characterized for anthocyanin and polyphenol total content in berries at harvest. Phenotypic variation for both traits was analyzed and analysis of variance (ANOVA) results showed significant differences due genotype effect (p < 0.001). Subsequently, this panel was genetically characterized by genotyping-by-sequencing (GBS) approach, and GWAS wereperformed for the polyphenol and anthocyanin total content, using a set of 116,751 good quality SNPs, the mixed linear model (MLM)and LIMMAsoftware. Our preliminary results showed significant association of a genomic region for the former at the chromosome (chr.) 6, while for the latter, highly associated SNPs were identified at chr. 1, 7, 13, and 17. In parallel, a set of 22 varieties exhibitingcontrasting phenotypes for polyphenol content (i.e. low content vs. high content) was analyzed to characterizing the metabolomic profiling of anthocyanin and polyphenolic compounds by HPLC. The ANOVA results revealed significant genotypic effects for syringetin-3-O-glucoside (p < 0.05) and resveratrol (p < 0.05). Also, significant genotype × phenotype group interactions were determined for ellagic acid (p < 0.001), gallic acid (p < 0.05), procyanidin B1 (p < 0.01), hyperoside (p < 0.05), quercetin-3-O-glucoside (p < 0.01), syringetin-3-O-galactoside (p < 0.01), and syringetin-3-O-glucoside (p < 0.05). Further studies including transcriptional and metabolite characterization are currently under development. Our ultimate goal is to identify biomarkers associated to polyphenol and anthocyanin metabolitesbiosynthesis pathways, and evaluating their potential application in MAS breeding programs.

Acknowledgements

Financed by ANID Chile grants 11190936 and FONDEF TA25I10087.