Gene expression related to the capsaicinoids biosynthesis in the Capsicum genus: Molecular and transcriptomic studies

A review of the gene expression relating to capsaicinoid biosynthesis was carried out, in different species and varieties, within the Capsicum genus. The results were obtained using different molecular approaches with a variety of species of Capsicum genus (mainly C. frutescens L., C. chinense Jacq. and C. annuum L.). The analysis of these results indicated that some genes determine the pungency or non-pungency in these species, mainly by recessive or non-functional alleles. In addition, the level of expression of other genes modulates the level of capsaicinoids. Environmental factors and abiotic stress influence the expression of candidate genes, impacting the capsaicinoid biosynthesis and, in turn, the fruit pungency. Other factors such as fruit tissue (placenta, pericarp) and plant varieties also influence the transcriptomic profile. Finally, the transcriptome approaches demonstrated gene regulation in the capsaicinoid biosynthesis pathway, and interestingly, in other genes responsible for the phenylpropanoids synthesis and the amino acid precursor synthesis, which also play a role in the capsaicinoids accumulation.