Unraveling cross-variations in fruit aroma and color during 'Red Delicious' bud sport: Insights from targeted...

During the movement of 'bud sports' in the 'Red Delicious', mature apple fruits transition from having vertical red stripes to being completely dark red; nevertheless, the fruit aroma exhibits a decrease in fragrance intensity. Hence, exploring the mechanism of cross-regulation of fruit color and aroma during continuous bud sports has significant biological implications. Here, metabolomic profiling of 110 anthocyanins and 1455 volatile compounds across 'Red Delicious' and four consecutive generations of bud sport mutants demonstrated an increase in Cyanidin-3,5-O-diglucoside and Cyanidin-3-O-glucoside accumulation, while a decline in Hexyl 2-methylbutanoate levels. Furthermore, integrated transcriptomic analysis further revealed that differential expression of crucial structural genes MdCHI, MdCHS, MdANS, MdUFGT, MdLOX, MdADH, and MdIPMDH provides a molecular basis for the metabolic changes. Ultimately, a gene regulatory network for variations in fruit aroma and color was constructed. Collectively, this present work furnishes a theoretical basis for apple variety improvements and future genetic manipulation.