Assessing diversity and clonal variation of Australia’s grapevine germplasm (Chardonnay)
Chardonnay is one of the dominant grapevine cultivars used for winemaking in Australia. There are now many clones of this variety, some of which have only recently become available in Australia. These clones exhibit variation in a number of viticultural and oenological traits including fruit composition, flavour and aroma profile, ripening time, flower morphology (leading to seedless grapes), bunch morphology, yield and grape colour. This project aims to assess the genetic variation among clones of Chardonnay available in Australia, and evaluate how this variation contributes to chemical and sensory variation in grapes and wines derived from the different clones.
Understanding genetic variation in Chardonnay
A reference genome for Chardonnay has now been completed for clone I10V1 with the use of new data from a long read PacBio sequencing platform. High coverage sequencing data obtained from 15-50 kb insert libraries on an RSII machine was used to augment pre-existing data to create a hybrid assembly that resolved this highly heterozygous genome. Mapping of short read sequence data to the new, highly contiguous and haplotype-resolved reference assembly is now under way. Once complete this will permit a comprehensive cataloguing of genetic diversity between clones. Genomic comparisons will initially focus on single base changes that differentiate clones and could subsequently be used as markers for differentiation of clonal material in the field. Ultimately comparisons will also include variations in genome structure including insertions and deletions.
Understanding of the genetic differences among clones will be combined with knowledge about their different behaviour in the vineyard and winery. This will include both chemical and sensory data from winemaking trials of multiple different Chardonnay clones, evaluated across multiple sites in multiple vintages.