Molecular Interaction of Genes Related to Anthocyanin, Lipid and Wax Biosynthesis in Apple Red-Fleshed Fruits

Transcriptomic analysis of fruit flesh of the cultivars 'Trinity' (red-fleshed) and 'Free Redstar' (white-fleshed) uncovered a set of ten genes involved in different metabolic pathways. Three-<i>N3Dioxy</i>, <i>LAR1</i> and <i>F3Mo</i>-were mapped via phenylpropanoid and flavonoid biosynthesis (mdm00940, mdm00941); four-<i>AlcFARed</i>, <i>CER1</i>, <i>Cyp86A4</i> and <i>PalmTransf</i>-were mapped on the cutin, suberine and wax biosynthesis pathways (mdm00073); and three-<i>TropRed</i>, <i>CyP865B1</i> and <i>CytP450</i>-were mapped via the tropane/piperidine/pyridine alkaloid biosynthesis pathway and the peroxisome pathway (KEGG:mdm00960, KEGG:mdm04146). Our study highlighted the higher activity of <i>AlcFARed</i>, <i>CER1</i>, <i>PalmTransf</i> and <i>CYP86A4</i> in red-fleshed apple fruits and allowed us to discover a specific relationship between significant reductions in fruit wax coating and anthocyanin enrichment in fruit flesh. In addition, the uncovered inhibition of the <i>TropRed</i> gene and the activation of both <i>Cyp865B1</i> and <i>CYP86A4</i> suggests that both compounds generate primary alcohols and alkanes, ultimately bound to wax formation. Our results postulate that the fatty acid degradation process is initiated in the flesh of apple fruits and depends on the relationship between anthocyanin content and lipid and wax metabolism. These findings further our understanding of the molecular mechanism linking anthocyanin and wax, making it significantly important in the context of apple fruit storage stability.