Overexpression of a carrot BCH gene, DcBCH1, improves tolerance to drought in Arabidopsis thaliana

Background: Carrot (Daucus carota L.), an important root vegetable, is very popular among consumers as its taproot is rich in various nutrients. Abiotic stresses, such as drought, salt, and low temperature, are the main factors that restrict the growth and development of carrots. Non-heme carotene hydroxylase (BCH) is a key regulatory enzyme in the beta-branch of the carotenoid biosynthesis pathway, upstream of the abscisic acid (ABA) synthesis pathway. Results: In this study, we characterized a carrot BCH encoding gene, DcBCH1. The expression of DcBCH1 was induced by drought treatment. The overexpression of DcBCH1 in Arabidopsis thaliana resulted in enhanced tolerance to drought, as demonstrated by higher antioxidant capacity and lower malondialdehyde content after drought treatment. Under drought stress, the endogenous ABA level in transgenic A. thaliana was higher than that in wild-type (WT) plants. Additionally, the contents of lutein and beta-carotene in transgenic A. thaliana were lower than those in WT, whereas the expression levels of most endogenous carotenogenic genes were significantly increased after drought treatment. Conclusions: DcBCH1 can increase the antioxidant capacity and promote endogenous ABA levels of plants by regulating the synthesis rate of carotenoids, thereby regulating the drought resistance of plants. These results will help to provide potential candidate genes for plant drought tolerance breeding.

Automated summary

The study demonstrates that the DcBCH1 gene can enhance plants' antioxidant capacity and internal ABA levels, improving their drought resistance. Furthermore, under drought stress, the expression levels of carotenogenic genes in transgenic plants significantly increased.