Abstract
BackgroundUnderstanding 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.ResultsOn 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 (FST = 0.162) between Qinghai-Tibet Plateau (QTP) and Xinjiang (XJC), and high differentiation (FST = 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.ConclusionThis 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.
Highlights
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
Each E. tangutorum accession in present investigation could be treated as a population consisting of seeds of neighboring individual plants collected from differently distant locations [63]
The within-accession variability is not determined by individual-based analysis, we have observed the high degree of differentiation within this species according to Unweighted Pair Group Method with Arithmetic (UPGMA) and principal coordinate analysis (PCoA) analysis based on bulked DNA samples
Summary
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. Is the largest and most widely distributed genus in the tribe Triticeae, with 150 species grown in temperate regions of the world [1]. This genus has a closer phylogenetic relationship with some of the important cereal crops, such as wheat, barley, rye and triticale [1]. Elymus tangutorum (Nevski) Hand.-Mazz, a perennial hexaploid species with the StYH genome (2n = 6x = 42), along with E. duhuricus Turcz. As one of the more important forage grasses in QTP, E. tangutorum has been widely studied. Most of studies mainly focused on the domestication, cultivation, phylogenesis and genome constitution [4, 6]
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