Abstract
Purple carrots accumulate abundant cyanidin-based anthocyanins in taproots. UDP-glucose: sinapic acid glucosyltransferase (USAGT) can transfer the glucose moiety to the carboxyl group of sinapic acid thereby forming the ester bond between the carboxyl-C and the C1 of glucose (1-O-sinapoylglucose). 1-O-sinapoylglucose can serve as an acyl donor in acylation of anthocyanins and generate cyanidin 3-xylosyl (sinapoylglucosyl) galactoside in purple carrots. This final product helps stabilize the accumulation of anthocyanins. In this study, a gene named DcUSAGT1 encoding USAGT was cloned from ‘Deep purple’ carrot taproots. Enzymatic activity was determined using high performance liquid chromatography (HPLC). The optimal temperature and pH value were 30°C and 7.0, respectively. Kinetic analysis suggested a Km (sinapic acid) of 0.59 mM. Expression profiles of DcUSAGT1 showed high expression levels in the taproots of all the three purple carrot cultivars but low expression levels in those of non-purple carrot cultivars. The USAGT activity of different carrots in vitro indicated that crude enzyme extracted from the purple carrot taproots rather than non-purple carrot taproots exhibited USAGT activity. These results indicated that DcUSAGT1 may influence anthocyanin biosynthesis of purple carrot taproots.
Highlights
As described in detail previously, carrots (Daucus carota L.) located in the second place in the aspect of economic value among all the vegetables in the European Union
Our work aimed to investigate the role of UDP-glucose: sinapic acid glucosyltransferase (USAGT) in anthocyanin biosynthesis of purple carrot taproots
Structure-based sequence alignment was performed on the DcUSAGT1 of other plant UDPglucose: glucosyltransferases (Fig 2), such as UDP-glucose: flavonoid 3-O-glucosyltransferase from Medicago truncatula (Accession No XP_003610163.1), UDP-glucose: anthocyanidin 3O-glucosyltransferase from Clitoria ternatea (Accession No 3WC4_A), UDP-glucose: flavonoid 3-O-glucosyltransferase from Vitis vinifera (Accession No AAB81682.1), cytokinin-Oglucosyltransferase from M. truncatula (Accession No XP_003618665.1), and UDP-glycosyltransferase 72B1 (UGT72B1) from A. thaliana (Accession No NP_192016.1)
Summary
As described in detail previously, carrots (Daucus carota L.) located in the second place in the aspect of economic value among all the vegetables in the European Union. They are important vegetable crops worldwide [1, 2]. Carrots are biannual diploids (2n = 2x = 18) with a comparatively small genome about 470 Mb [3]. Carrots are rich in a variety of nutrition, such as carotenoids, hydroxycinnamic acids, anthocyanins, potassium, vitamin B6, vitamin C, folic acid, and magnesium [6]. Atrorubens Alef.) accumulate rich anthocyanins in taproots.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
