Ectopic expression of citrus UDP-GLUCOSYL TRANSFERASE gene enhances anthocyanin and proanthocyanidins contents and confers high light tolerance in Arabidopsis

Abstract

BackgroundCitrus fruits are consumed freshly or as juice to directly provide various dietary flavonoids to humans. Diverse metabolites are present among Citrus genera, and many flavonoids biosynthetic genes were induced after abiotic stresses. To better understand the underlying mechanism, we designed experiments to overexpress a UDP-GLUCOSYL TRANSFERASE gene from sweet orange (Citrus sinensis) to evaluate its possible function in metabolism and response to stress.ResultsOur results demonstrated that overexpression of Cs-UGT78D3 resulted in high accumulation of proanthocyanidins in the seed coat and a dark brown color to transgenic Arabidopsis seeds. In addition, the total contents of flavonoid and anthocyanin were significantly enhanced in the leaves of overexpressed lines. Gene expression analyses indicated that many flavonoid (flavonol) and anthocyanin genes were up-regulated by 4–15 folds in transgenic Arabidopsis. Moreover, after 14 days of high light stress, the transgenic Arabidopsis lines showed strong antioxidant activity and higher total contents of anthocyanins and flavonoids in leaves compared with the wild type.ConclusionOur study concluded that the citrus Cs-UGT78D3 gene contributes to proanthocyanidins accumulation in seed coats and confers tolerance to high light stress by accumulating the total anthocyanin and flavonoid contents with better antioxidant potential (due to photoprotective activity of anthocyanin) in the transgenic Arabidopsis.

Expression Profiling of Flavonoid Biosynthesis Genes and Secondary Metabolites Accumulation in Populus under Drought Stress

“…The plants with higher antioxidant activity or capacity show more resistance against drought stress [52], and those with lower antioxidant activity or capacity are susceptible to drought stress [53]. Prolonged exposure to drought and high light stress enhanced antioxidant activity and capacity in citrus plants [54,55]. In our experiments, increased exposure to drought stress of poplar plants also increased their antioxidant capacity and activity (Figure 6A−B).…”

Blue Light Acclimation Reduces the Photoinhibition of Phalaenopsis aphrodite (Moth Orchid)

“…Besides that, anthocyanin has a photoprotective effect on the PSII [27]. It has been reported that Arabidopsis confers a better antioxidant potential and tolerance to high irradiation stress by increasing the anthocyanin content [28]. The moth orchid is highly sensitive to high irradiation because whenever the light intensity is above 300 µmol m −2 s −1 , the ETR and qP levels were significantly reduced (Figure 1), indicating damage to PSII.…”

Genomic insights into citrus domestication and its important agronomic traits

“…(2019) 27 CsCYP75B1 Sweet orange A. thaliana Flavonoid biosynthesis Rao et al. (2020) 28 CsUDP78D3 Sweet orange A. thaliana Anthocyanin Rao et al. (2019b) 29 CgRuby1 , CgRuby2 , AbRuby2 Atalantia and pummelo A. thaliana Huang et al.…”