Study On Population Genetic Structure Of Elymus Shandongensis

Barley yellow dwarf virus (BYDV) is a pathogen caused serious yield losses incereals, which spread by aphids. Also, the growth of plants has important influence onthe quality of the soil. Plant diseases and soil quality are the important factors thataffect agricultural development. Here, we present a study on the diversity andpopulation differentiation at molecular markers linked to Barley yellow dwarf virus(BYDV) resistance genes across14Elymus shandongensis populations from islandand mainland regions in Shandong Province of China and the influence of three kindsof forage grass on soil quality.All the27loci were polymorphic, exhibiting81alleles. The overall geneticdiversity was relatively high (He=0.380, I=0.548), with considerable variation withinand among regions. The population from the Zhucha island (Z) showeda higher levelof genetic diversity (He=0.417I=0.596), whereas the populationfrom the Lingshanisland (L) had a higher level of genetic diversity (He=0.304I=0.434).Significantcorrelation between genetic diversity and geographical distance existed among islandpopulations (R2=0.3353, P<0.0001). The data also showed the highest level of geneticdifferentiation in Lingshan island (ΦRT2=0.199), and the lowest level of geneticdifferentiation was in Yangkou region (ΦRT2=0.016).AMOVA analysis also confirmedthis model.This indicated that BYDV may have higher selection within a region.UPGMA tree and the Structure analysis indicated that almost all island populationswere closely related to mainland populations except the L1population. This geneticvariation pattern is probably associated with several factors, such as the polymorphismfeature of R-genes, isolation, BYDV selection, and immigrants.The samples came from Mayu Town of Jinzhou City, Hebei Province. Study weremeasured soil pH, soil microbes, and soil enzyme activities at two depth levels (0-20cm and21-40cm) of the rhizosphere soils of three pastures intercropping and thecorrelation between above factors. Five results were obtained. Firstly, pH values, fungi numbers, actinomycetes numbers, and urease activity differed at two depth levels.Secondly, pH values, actinomycetes numbers, and peroxidase activity (0-20cm) werehighly improved by the intercropping Orychophragmus violaceus (L.)Schulz. Whereasurease activity was decreased in this intercropping plot.Thirdly, pH value wasdecreased in the intercropping Poa.annua L. plot, and fungi numbers (0-20cm) andperoxidase activity were highly improved. Fourthly, peroxidase activity was decreasedand urease activity was highly improved in the intercropping Lolium perenne L. plot.Finally, there had significantly positive correlation between pH values and soil depths,between peroxidase activities and actinomycetes numbers, between peroxidaseactivities and pH values, and between actinomycetes numbers and pH values; there hadsignificantly negative correlation between actinomycetes numbers and soil depths,between urease activities and soil depths, and between urease activities and pH values;and there had significantly correlation between actinomycetes numbers andintercropping pastures. Therefore, the soil quality possible had more improvementwhen Orychophragmus violaceus(L.)Schulz) and Poa annua L were simultaneouslyplanted between pears.