Effect of the Carotenoid Content and Activity of the Carotene cis-trans Isomerase CRTISO on Tomato Fruit Color

Abstract

The tomato Solanum lycopersicum L. is a convenient model for studying carotenoid metabolism due to the wide variety of carotenoid-mediated pigmentation of the ripe fruit. Carotene cis-trans isomerase CRTISO catalyzes cis-trans isomerization of double bonds leading to the formation of all-trans-lycopene, which is the most powerful antioxidant among carotenoids and a substrate for subsequent synthesis of α-, β-carotenes, and xanthophylls. In this work, 18 accessions of tomato cultivars and lines differing in the color of ripe fruit have been analyzed. The obtained biochemical data showed a dependence of fruit color on the content and composition of carotenoids and the presence or absence of chlorophylls. Expression analysis of three CRTISO homologous genes performed in silico has shown that the highest expression level in the fruit is only characteristic of gene CRTISO that has the maximal transcription at the stages of color change (from green to red) and biological ripeness of the fruit. Quantitative real-time PCR did not reveal any strong correlation between the level of CRTISO gene expression and total carotenoids, which may be explained by a different quantity of metabolites preceding prolycopene.