Treffer: Genomic investigation for markers linked to fruit and bunch quality traits in grapevine

Thesis (MScAgric)--Stellenbosch University, 2022. ; ENGLISH ABSTRACT: Grape production faces several challenges such as climate change, pests, diseases, and new demands from consumers and growers. Breeding programmes offer a solution by creating new cultivars that can maintain yield and quality in changing environmental conditions while providing fruit that appeals to the wine and table grape global market. Modern breeding methods now integrate genomic tools with traditional practices to increase the selection efficiency and precision of cultivar improvement. Genomic tools such as molecular markers are developed using knowledge of the underlying genetics and inheritance of a trait. In grapevine, very few markers exist for fruit quality due to the lack of information on the genetic basis of important agricultural traits. Compactness is a key grapevine breeding target and refers to the arrangement of berries within a bunch. This trait impacts both disease resistance and fruit quality as highly dense bunches tend to be more susceptible to fungal infections and uneven berry ripening. Compactness is strongly influenced by cluster architecture traits that includes several bunch, berry, and rachis characteristics. Quantitative Traits Loci (QTL) mapping has previously been used to elucidate the genetic determinants of cluster architecture however, no stable QTLs that are consistent across different genetic and environmental backgrounds have been identified. To detect robust QTLs, a meta-analysis was performed for grapevine fruit and bunch morphology traits. Using the BioMercartor program, a consensus map was built by integrating genetic maps from 26 previously published grapevine studies, onto which a total of 258 QTLs from 15 previous QTL studies distributed on 18 chromosomes were projected. Twenty-four meta-QTLs were identified for fruit and cluster architecture traits and further genomic investigation of these new regions revealed 16 putative candidate genes. These genes were classified as regulatory, growth and ...