[Seed morphology and germination characteristics of Tripterygium wilfordii].

The seeds of Tripterygium wilfordii are characterized by dormancy and a long germination cycle under natural sowing conditions. In this study, we developed a method for rapid germination of T. wilfordii seeds by analyzing the size, morphology, thousand-grain weight, viability, moisture content, physicochemical properties, and seed germination rates under different germination conditions. The seeds of T. wilfordii were fine columnar with a thick and hard outer seed coat. They had the length of 6.69 mm, the width of 2.14 mm, the thickness of 1.68 mm, the thousand-grain weight of 8.99 g, the moisture content of 8.86%, the soluble sugar content of 21.3 mg·g~(-1), the starch content of 28.9 mg·g~(-1), the soluble protein content of 44.2 mg·g~(-1), and the seed viability of only 54.0%. The seeds were respectively treated with distilled water, ultrasonication, low-temperature storage, 50 ℃ water, 100 mg·L~(-1) 6-BA, 0.6% KMnO_4, 1% KNO_3, 50 mg·L~(-1) NAA, and 100 mg·L~(-1) GA_3 solution. The results showed that soaking the seeds in 100 mg·L~(-1) GA_3 solution significantly promoted the germination. Further, the seeds were soaked in 50, 100, 250, 500, and 1 000 mg·L~(-1) GA_3 solutions, which demonstrated that high concentration(500 mg·L~(-1), 1 000 mg·L~(-1)) of GA_3 solutions increased the germination rate and speed and shortened the germination cycle from more than 3 months to less than 15 days. The findings of this study are of great significance to the breeding of T. wilfordii and lay a foundation for the large-scale propagation of T. wilfordii seeds and the excavation of T. wilfordii germplasm resources.

Isolation and characterization of a glycosyltransferase with specific catalytic activity towards flavonoids from Tripterygium wilfordii.

Flavonoids are important secondary metabolites that exist in many medicinal plants. Flavonoid glycosyltransferases can transfer sugar moieties to their parent rings, producing various flavonoid glycosides with significant pharmacological activities. Here, we report the molecular cloning of the O-glycosyltransferase TwUGT2 from Tripterygium wilfordii and its catalytic activity was explored by heterologous expression in E. coli. The results showed that TwUGT2 has specific glycosyltransferase activity towards C-3 and 7 hydroxyl groups of flavonoids, thereby converting quercetin and pinocembrin into isoquercitrin and pinocembrin 7-O-beta-D-glucoside, respectively. The identification of TwUGT2 will provide a useful molecular tool for synthetic biology and contribute to drug discovery.[Formula: see text].