| Summary: | 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 <i>DcPSY1</i>, <i>DcPSY2</i>, <i>DcZDS1</i>, <i>DcCRT1</i> and <i>DcCRT2</i> increased significantly in both ‘KRD’ and BHJS’ under salt stress, but <i>DcCHXE</i> transcripts decreased and <i>DcPDS</i> transcripts maintained a basal level compared to that of the control. In the taproot of ‘KRD’, the expression level of <i>DcLCYB</i>, <i>DcLCYE</i> and <i>DcCHXB1</i> 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 <i>DcLCYE</i> and <i>DcCHXB1</i> transcripts. The increase in β-carotene accumulation is speculated to increase salt tolerance.
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