Abstract

The processing industries demand concrete specifications from its providers, most quality factors for processed Capsicum are related to the pericarp fruit thickness, total soluble solids, yield of fresh and dry fruit, color ripening, and total carotenoid. Characterizations of Capsicum germoplasnm properties are extremely valuable to the processing industry but also for Capsicum breeding program. 50 Capsicum annuum L. accessions, dark-brown (DB), red (R) and yellow (Y) fruit, were evaluated for industry traits (pericarp fruit thickness, total soluble solids, yield of fresh and dry fruit). Afterward, seven accessions were selected for further analysis in terms carotenoid accumulation and carotenoid biosynthetic gene expression. The different genotypes show genetic variation in fruits, in terms pericarp thickness, total soluble solids, yield of fresh and dry fruit. Among them, pericarp fruit thickness showed highest genetic variability (0.87 – 8.5mm), while total soluble solids showed slighter genetic variability (5,50 -15,75°Brix). Genetic variability for dry fruit yield, present at levels ranging from 3,44 to 20,97 % dry matter. Accumulation of total carotenoid and chlorophyll degradation at the fully ripe stage were evaluated by spectrophotometry and HPLC. Significant differences were observed for total carotenoid accumulation and chlorophyll degradation among the different Capsicum genotypes (p<0.005); Red-fruits Capsicum (A-571, A-1777, A-664) showed highest carotenoid accumulation. Yellow fruits Capsicum (A-580, A-583) showed lower carotenoid accumulation. The Capsicum dark-brown fruits (A-612, A-658) showed lowest carotenoid accumulation and higher chlorophylls content (2 to 5 fold higher than red and yellow fruit genotypes), suggesting that those fruits did not achieve total ripening. Several studies have demonstrated that carotenoid accumulation is mainly controlled by the transcriptional regulation of carotenoid biosynthetic genes; for this study lycopene-b-cyclase and capsanthin-capsorubin synthase gene expression was assessed by RT-PCR. Dark-brown (DB) and red (R) Capsicum genotypes showed capsanthin-capsorubin synthase gene expression. Capsicum genotypes A-664 and A-658 showed higher capsanthin-capsorubin synthase gene transcripts accumulation (> 3.5 fold). All of the ripe Capsicum fruits, showed lycopene-b-cyclase gene expression. Capsicum red fruit A-664 showed significant highest transcripts level accumulation (1.7 fold) and dark-brown fruit A-612 showed significant lowest transcripts accumulation (0.2 fold). For Capsicum red fruit, the total carotenoids accumulation showed higher association with capsanthin-capsorubin synthase transcripts level. Similar results were observed for Capsicum dark-brown fruits, the total carotenoid accumulation was highly associated with capsanthin-capsorubin synthase transcripts accumulation. For yellow fruit Capsicum, the total carotenoids present higher association with lycopene-b-cyclase transcripts accumulation. This study supports previous studies, indicating lack of capsanthin-capsorubin synthase transcripts expression in Capsicum yellow fruits.