Chemical and molecular identification of sweet pitaya (Stenocereus thurberi) fruit variants with different pulp coloration

Abstract

Sweet pitayas are fruits produced by Stenocereus thurberi. The pulp's fruit is strikingly colored due to the presence of pigments known as betalains. Some chemical and proximal attributes of sweet pitayas vary according to fruit's pulp color suggesting that each variant has a specific nutritional value and genetic information. DNA barcoding is a potential tool to identify the genetic variability of individuals producing different colored pitayas, which can discriminate among variants. In this study, a chemical and a proximal analysis using the pulp of orange, red, and pink sweet pitayas from Sonora (Mexico) were performed. A cluster analysis using pulp color data was carried out to identify clusters of individuals producing the same color. In addition, single and multi-locus barcodes using rbcL, matK and trnH-psbA loci were used to identify possible genetic differences among individuals that produce orange, red, pink, and white sweet pitayas from Sonora. Phylogenetic trees using UPGMA and Kimura-2-Parameter were performed to evaluate the differences among color groups with single and multi-locus barcodes. Some chemical components of pitaya's pulp (i.e., betalains, protein, and titratable acidity), vary according to fruit pigmentation, suggesting that each variant has a specific composition of metabolites. The multi-locus DNA barcode rbcL + matK + trnH-psbA was the best alternative for identifying the genetic diversity of individuals producing sweet pitaya variants of different colors. This approach demonstrates a strong potential for rapid and efficient identification of the biological diversity of pitaya variants, offering an alternative to traditional taxonomic methods.