GENOMIC BREEDING OF BLACKBERRY FOR IMPROVED FIRMNESS AND POSTHARVEST QUALITY

Our long-term goal is to develop new crispy blackberry cultivars with enhanced firmness and superior postharvest performance. The primary objective of this proposal is to implement marker-assisted selection for texture in the UA fruit breeding program to reduce breeding cycle time and expedite the process of combining crispy texture with other desirable traits. Based on preliminary results in blackberry and studies in other Rosaceae fruit crops, we hypothesize that variation in fruit firmness in fresh-market blackberries is determined by mutations in a few gene(s) related to polysaccharide-modifying enzymes. We further hypothesize that crispy texture may be recessively inherited, with four copies of a non-functional allele at a gene coding for a polysaccharide-modifying enzyme, such as polygalactonurase (PG), necessary to recover crispy texture. Allele dosage at this gene may contribute other quantitative variation in flesh firmness seen in the UA blackberry breeding program. We will leverage the new tools we have developed including two diploid reference genomes, a tetraploid blackberry resequencing panel, and a high throughput phenotyping protocol for red drupelet reversion to test these hypotheses and understand the underlying genetics controlling texture variation in cultivated blackberries.