Genetic bases of fruity notes (fresh and dried) of the Nacional cocoa variety

Theobroma cacao is the only source of cocoa. Cocoa is classified into two types of products: bulk cocoa and fine flavour cocoa. Contrary to bulk cocoa, fine aromatic cocoa is characterized by its floral and fruity aromas [1]. In order to understand the genetic determinism of the formation of these aromas in cocoa beans, a genetic study using the Genetic Wide Association Study (GWAS) method was undertaken. It was carried out on 158 clones belonging to a population of Nacional tree type cultivated in Ecuador, whose volatile compound concentrations and sensory profiles were characterized for its diversity. This study revealed areas of correlation between, on the one hand, the genetic diversity of this population, revealed by molecular marker alleles and the volatile compounds detected in the different clones, and on the other hand, between this same genetic diversity and their sensory profiles. These correlation zones, also called associations, are therefore linked to one of these traits, but also in some cases to both types of traits. Thanks to these associations, which correspond to a restricted area of the cocoa genome, and the knowledge of its complete sequence [2], candidate genes have been brought to light. Some of them are known and identified in biosynthesis pathways of volatile compounds, which are themselves known to have a fruity note. In a preliminary study, a difference in the expression of these genes was identified between four genotypes (two floral and two fruity genotypes) during different stages of development and fermentation of the beans. The results showed that the candidate genes tended to be activated during fermentation and not during the maturation stages of the pods