Effect of 2-(4-chlorophenylthio) ethylamine hydrochloride on lycopene biosynthesis in pepper fruits

Abstract

Lycopene is an intermediate metabolic product of the capsanthin biosynthesis pathway in pepper fruits and is one of the strongest antioxidants found in plants. During the ripening of pepper fruits, lycopene is almost completely transformed into the downstream metabolic product capsanthin as well as other substances. As a result, lycopene cannot be enriched in ripe pepper fruits; however, the lycopene content can be increased by 2-(4-chlorophenylthio) ethylamine hydrochloride (CPTA) treatment, using the optimal concentration at the optimal development stage of pepper fruits. The current study tested different CPTA concentrations and fruit developmental stages to increase the lycopene content in pepper fruits. The results showed that the lycopene content was significantly enriched in pepper fruits treated with 0.1% CPTA applied at the turning stage. Real-time quantitative polymerase chain reaction analysis showed that CPTA treatment significantly promoted the expression of the upstream genes (Psy and PDS) involved in the anabolic metabolism of lycopene; however, CPTA treatment had a significant inhibitory effect on the downstream gene (Lcyb) of lycopene synthesis. Therefore, in pepper fruits, CPTA inhibits the normal expression of the Lcyb gene downstream of lycopene, thus achieving notable lycopene enrichment.