Potential of Arabica coffee genotypes for bean quality

Abstract

Research on Coffea arabica aimed at obtaining promising genotypes for grain quality has advanced in various fields, including genetic improvement, fruit biochemistry, and the study of genes related to coffee development and quality. This thesis will address these areas in three manuscripts. The first manuscript conducted a phenotypic and genotypic characterization of 14 progenies derived from the Mundo Novo cultivar. High genetic and phenotypic variability was observed both between and within progenies. Intracultivar variation was also evident in commercial cultivars, highlighting that this characteristic is common in arabica coffee. This variability present in C. arabica paves the way for the identification of superior genotypes and the development of genetically more homogeneous lines, contributing to greater efficiency in breeding programs. In the second manuscript, analyses of carbohydrate and differentially abundant metabolites (DAMs) were performed, indicating significant variations, particularly in the early perisperm stage, with greater cultivar distinction at 30 days after flowering (DS1). Compounds such as D-ribose and D-fructose were found to be similar among some cultivars only at DS1, whereas significant differences were observed in metabolites related to glycolysis and the tricarboxylic acid cycle, both of which are involved in the formation of quality-related precursors. Finally, considering the essential role of sucrose in plants and its relevance as a precursor of coffee flavor components, the third manuscript investigated invertase genes, enzymes responsible for the irreversible cleavage of sucrose. A total of 65 genes were identified in three Coffea species, including 28 in C. arabica, and 18 and 19 in modern representatives of its parent species, C. canephora and C. eugenioides, respectively. Polyploidization is likely the main cause of the expanded number of invertase genes in C. arabica. Expression analyses revealed both constitutive and conditional patterns across different fruit developmental stages, providing new insights for functional studies, particularly in the economically important species C. arabica and C. canephora. Therefore, this study aimed to expand knowledge about the factors determining the quality of C. arabica beans, contributing to the development of promising cultivars aligned with global market demands, thus enhancing the value of the coffee production chain.