Abstract
Flavonoids are major secondary metabolites in Camellia sinensis. Flavanone-3-hydroxylase (F3H) is a key enzyme in flavonoid biosynthesis in plants. However, its role in the flavonoid metabolism in C. sinensis has not been well studied. In this study, we cloned two F3Hs from C. sinensis, named CsF3Ha and CsF3Hb, where CsF3Ha containing 1107 bases encoded 368 amino acids, and CsF3Hb containing 1071 bases encoded 357 amino acids. Enzymatic activity analysis showed both recombinant CsF3H enzymes in Escherichia coli could convert naringenin and eriodictyol into dihydrokaempferol (DHK) and dihydroquercetin (DHQ), respectively. The expression profiles showed that CsF3Ha and CsF3Hb were highly expressed in the tender leaves of tea plants. Under different abiotic stresses, the two CsF3Hs were induced remarkably by ultraviolet (UV) radiation, sucrose, and abscisic acid (ABA). In the seeds of CsF3Hs transgenic Arabidopsis thaliana, the concentration of most flavonol glycosides and oligomeric proanthocyanidins increased significantly, while the content of monocatechin derivatives decreased. The present study revealed that CsF3Hs played critical roles in flavonoid biosynthesis in tea plants.
Highlights
Flavonoids are widely distributed in plants, and have the medicinal functions of cerebral ischemia injury prevention, analgesia, and antineoplastic activity [1]
Shoots were treated under 90 mM/L sucrose, 200 mM/L mannitol, 50 mM/L NaCl, 10 μM/L jasmonic acid (JA), 0.74 μM/L indolebutyric acid (IBA), 100 μM/L abscisic acid (ABA), and 20 mM/L salicylic acid (SA) for 12 and 48 h, respectively
The results suggested that CsF3Ha and CsF3Hb exhibited high expression in the leaves (Figure expression profiles in second leaves atleaf, different were consistent with flavonoid tender leaves such5).asTheir the bud, first leaf, and andstages low expression in the fourth and old accumulation patterns in tea plants [2]
Summary
Flavonoids are widely distributed in plants, and have the medicinal functions of cerebral ischemia injury prevention, analgesia, and antineoplastic activity [1]. A. thaliana improved tolerance to salt stress and ABA treatment by alleviating the inhibitory effects of naringenin on plant growth and changing the flavonoid components in transgenic plants [18]. In Reaumuria soongorica, the increases of RsF3H gene expression, RsF3H enzyme activity and the antioxidative ability of the metabolic end products in the flavonoid biosynthetic pathway enhanced the stress tolerance to ultraviolet (UV)-B radiation and drought [19]. CsF3Hs was conducted including multiple sequence alignment, phylogenetic analysis, gene function verification, and response to abiotic stresses
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