Abstract
BackgroundCarrot (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 β-branch of the carotenoid biosynthesis pathway, upstream of the abscisic acid (ABA) synthesis pathway.ResultsIn 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 β-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.ConclusionsDcBCH1 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.
Highlights
Carrot (Daucus carota L.), an important root vegetable, is very popular among consumers as its taproot is rich in various nutrients
Isolation and sequence analysis of DcBCH1 The full-length open reading frame (ORF) of DcBCH1 obtained from carrot (‘Kurodagosun’ and ‘Junchuanhong’) was 930 bp, encoding 309 amino acids, and some differences were observed between the two sequences at the nucleotide and amino acid levels
Sequence alignment results showed that DcBCH1 from carrot (‘Kurodagosun’ and ‘Junchuanhong’) had the highest similarity with β-carotene hydroxylase from Apium graveolens (AgBCH1) and the lowest similarity from Cucurbita moschata (CmBCH1)
Summary
Carrot (Daucus carota L.), an important root vegetable, is very popular among consumers as its taproot is rich in various nutrients. Non-heme carotene hydroxylase (BCH) is a key regulatory enzyme in the β-branch of the carotenoid biosynthesis pathway, upstream of the abscisic acid (ABA) synthesis pathway. The violaxanthin can be reconverted to zeaxanthin under violaxanthin de-epoxidase (VDE) catalysis. This process is called the xanthophyll cycle [6, 7]. Violaxanthin and neoxanthin can produce plant hormone, abscisic acid (ABA), under the action of 9-cis-epoxycarotenoid dioxygenase (NCED) [8]. Non-heme carotene hydroxylase, BCH ( called CHY, HYD, or HYb), is one type of carotene hydroxylase that is involved in regulating the synthesis of carotenoids in some species. In sweet orange, silencing the expression of β-carotene hydroxylase gene (Csβ-CHX) by RNA interference increased the β-carotene content in the pulp of the silenced plant by 36 fold [10]
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