Changes in Carotenoid Concentration and Expression of Carotenoid Biosynthesis Genes in Daucus carota Taproots in Response to Increased Salinity

Abstract

Studying the changes of carotenoids in the taproot of carrots under salt treatment is helpful to probe the salt stress response mechanism of carrots. The carotenoid concentration and the expression profiles of 10 carotenoid-related genes were determined in two carrot cultivars with different taproot colors. Under salt stress, the biosynthesis of carotenoids in the taproot of both ‘KRD’ and ‘BHJS’ was activated. RT-qPCR manifested that the expression levels of DcPSY1, DcPSY2, DcZDS1, DcCRT1 and DcCRT2 increased significantly in both ‘KRD’ and BHJS’ under salt stress, but DcCHXE transcripts decreased and DcPDS transcripts maintained a basal level compared to that of the control. In the taproot of ‘KRD’, the expression level of DcLCYB, DcLCYE and DcCHXB1 climbed dramatically. However, there was no significant change in the taproot of ‘BHJS’. The study showed that salt stress can stimulate the biosynthesis of carotenoids. The accumulation of lutein in the taproots of ‘KRD’ and ‘BHJS’ may be mainly attributed to the variation in DcLCYE and DcCHXB1 transcripts. The increase in β-carotene accumulation is speculated to increase salt tolerance.