Genetic diversity and structure of Elymus tangutorum accessions from western China as unraveled by AFLP markers.

BACKGROUND: Understanding genetic diversity of wild plant germplasm and the relationships between ecogeographic and genetic characteristics may provide insights for better utilizing and conserving genetic resources. Elymus tangutorum (Nevski) Hand.-Mazz, a cool-season hexaploid perennial, is an important pasture bunchgrass species used for forages and grassland restoration in Qinghai-Tibet Plateau and northwest China. In this study, 27 E. tangutorum accessions from diverse origins of western China were evaluated using AFLP markers in an effort to delve into the genetic relationships among them. The effects of eco-environmental factors and geographical isolation on the genetic diversity and population structure were also elucidated. RESULTS: On account of 554 polymorphic fragments amplified with 14 primer combinations, the mean values of some marker parameters including polymorphic information content, resolving power and marker index were 0.2504, 14.10 and 23.07, respectively, validating the high efficiency and reliability of the markers selected. Genetic dissimilarity index values among accessions ranged from 0.1024 to 0.7137 with a mean of 0.2773. STRUCTURE, UPGMA clustering and PCoA analyses showed that all accessions could be divided into the three main clusters; however, this results do not exactly coincide with geographic groups. We found medium differentiation (F ST = 0.162) between Qinghai-Tibet Plateau (QTP) and Xinjiang (XJC), and high differentiation (F ST = 0.188) among three Bayesian subgroups. A significant correlation (r = 0.312) between genetic and geographical distance was observed by Mantel test in the species level, while the weak correlation was detected between genetic and environmental distance for all accessions and most of geographical groups. In addition, a significant ecological influence of average annual precipitation on genetic distance was revealed in XJC group and the Bayesian subgroup A. CONCLUSION: This study indicates that AFLP technique are a useful tool to measure genetic diversity in E. tangutorum, showing that geographical and environmental factors (especially precipitation) together, play a crucial role in genetic differentiation patterns. These findings underline the importance of local adaptation in shaping patterns of genetic variability and population structure in E. tangutorum germplasm collected in Western China.

[Determination of ellagic acid, flavonoids and goshonoside-F5 in Rubi Fructus by HPLC].

High-performance liquid chromatographic coupled with variable wavelength detection (HPLC-VWD) has been developed for simultaneous determination of 5 analytes including ellagic acid, quercetin, kaempferol-3-O-beta-D-rutinoside, tiliroside and kaempferol, and high-performance liquid chromatographic with an evaporative light scattering detector (HPLC-ELSD) has been established to determine goshonoside-F5 in extract of Rubi Fructus. Chromatographic separations were carried out on an Agilent ZORBAX SB-C18 column (4.6 mm x 250 mm, 5.0 microm). All calibration curves of reference standards revealed good linearity (R2 > 0.999 5) within the concentration ranges tested. The method limits of detection ranged 0.297-90.144 ng and the method limits ofquantitation ranged 0.990-300.480 ng, respectively. Recoveries of 6 analytes were from 97.11% to 101.7%, with RSD less than 2.1%. The result shows that amounts of the 6 analytes in the samples from 16 localities were found to be different. The higher latitude of growing environment, the more ellagic acid in herb. The content of total flavonoids in sample from east localities were higher than that in middle and west localities, and the content of goshonoside-F5 in Bozhou, Anhui province was higher than others. This method was found to be simple, accurate, sensitive with good repeatability. Those results might serve as a sound foundation for further study, quality control and application of Rubi Fructus.