Increasing Strawberry Nutritional Quality: Marker Assisted Selection Based on Co-Localization of mQTLs and e-QTLs Linked to Fruit Polyphenol Content

Strawberries belong to the Rosaceae family, are economically important fruits. Fragaria vesca a diploid specie is considered a model organism for cultivated strawberry (Fragaria x ananassa), an octoploid specie (2n=8x=56). Berries, including strawberries, are known for their rich nutritional profile, mainly for the high content in polyphenols which confers a greater antioxidant capacity. Understanding the genetic bases controlling the production of these phenolic compounds is extremely important for the selection of new varieties of cultivated strawberry with a greater nutritional profile.

LC-MS analysis for polyphenol metabolites in full ripen fruits from cultivated strawberry F2 population (CamarosaxDover) allowed the quantification of 22 different metabolites and mapping 146 mQTLs (metabolic QTLs) in the genetic linkage map. CxD genetic linkage map has been improved, possessing now 192 loci distributed along the 28 expected linkage groups, representing each homeologous group a high coverage (>70%) when compared with F. vesca genome. Gene expression levels of ripen fruit were analyzed after a microarray hybridiziation, containing all diploid genes, with RNA of all population individuals. Those genes which expression levels vary significantly have been selected for eQTLs analysis (expression QTLs), detecting 333 eQTLs.

The co-localization between mQTLs and eQTLs indicate a possible direct implication of candidate gene and accumulated metabolite. All co-localization were detected and the best results were then selected for a deeper analysis for trying to understand the biological context of those co-localizations. Target markers close to the position of mQTLs and eQTLs co-localization were considered as great candidates for marker assisted selection (MAS).