Unveiling the molecular mechanism involving anthocyanins in pineapple peel discoloration during fruit maturation

Peel color is a key factor that affects the fruit’s aesthetic and economic values. In Red Sugar pineapple, the peels’ red color reduces during maturation. Limited knowledge is available on the regulation of pineapple peel discoloration, which makes it important to study the molecular mechanisms associated with this important trait. Here, we report that a decrease in anthocyanin biosynthesis is predominantly associated with the pineapple peel color change during maturation. Particularly the exclusive accumulation of cyanidin in 60 days after flowering (DAF) as compared to 120 DAF gives the fruit peel its distinct reddish color. Our findings suggest that the changes in the expression of key structural genes (early and late biosynthetic genes) of the anthocyanin (cyanidin) biosynthesis pathway are responsible for peel discoloration. Based on a gene co-expression analysis and a transient expression, we identified two transcription factors i.e., AcHOX21 and AcMYB12, and showed that their downregulation leads to the reduced anthocyanin accumulation with fruit maturation. Comparative gene expression profiling analysis of RNA-seq data for pineapple peels harvested on 60, 90, and 120 days after flowering (DAF).