Relationship between Fruit Maturation, Phytochemical Content, Pungency, and Pun1 Gene Expression in Capsicum Species (Capsicum spp.)

This study investigates the effects of fruit maturation on phytochemical contents, pungency components and Pun1 gene expression in Capsicum species (C. annuum L., C. baccatum L., and C. chinense Jacq.). Fruits were collected at 20, 40 and 60 days after flowering and analyses were carried out during these periods. Total phenolic content increased after flowering, with a significant increase at 40 days and a further increase at 60 days. The total antioxidant content increased until day 40, but decreased until day 60. Flavonoid content increased until day 40 and then decreased, while carotenoid content increased continuously over time. Capsaicinoid content increased after flowering in species other than C. annuum. In C. annuum, capsaicinoid content increased until day 40, but decreased significantly until day 60. This trend correlated with Pun1 gene expression, which peaked at 40 days and decreased significantly by 60 days. Strong correlations were observed between Pun1 gene expression and phytochemical contents, with high levels of Pun1 gene expression associated with high phenolic and flavonoid contents. Similarly, antioxidant and carotenoid levels were higher during periods of maximum Pun1 gene expression. These results suggest that the Pun1 gene plays a crucial role in the maturation process and is a critical regulator of phytochemical accumulation. This study highlights the effects of fruit maturation on phytochemical content and gene expression, and elucidates the relationships between these compounds. The dynamics of phytochemical content and Pun1 gene expression during maturation provide insights for quality control and nutritional value in pepper cultivation.