Evaluation For Salt Tolerance And Screening Of SSR Markers Associated With Salt Tolerance In Barley

Barley is one of the important crops as food, feed and industry use. Yield loss resulted from salt stress annually, so development of salt-tolerant varieties using barley diverse germplasm is an available way to resolve the yield loss caused by salt stress and selection of some well-suited, efficient and stable salt-tolerant index is the important prerequisite for conventional barley breeding. Barley genome is full of abundant allelic variations, and discovering these alleles from genes related to salt tolerance is the basis of barley breeding, as well as understanding the complex genetic and molecular mechanism underlying salt tolerance. With the development of molecular biology and widely used in agriculture, identifying and screening marks related to salt tolerance and the used of molecular marker assisted selection breeding technology will greatly promote the barley genetic improvement and germplasm creation.In this study, a total of7barley cultivars were evaluated for salt tolerance with11traits using hydroponics and potted culture method respectively. And a total of100barley cultivars/accessions of divers origin were used as tested materials using hydroponics method. One hundred and seven SSR markers in barley7chromosomes were adopted to explore the genetic diversity of barley. Moreover, association analyses of10agronomic and physiological traits of barley were conducted in this study. The major results obtained were as follows:1. Variability in response to salinity was examined in7cultivars at seedling growth stage. Fresh weight of stem leaf and root, seedling height, leaf age, the activity of superoxide dismutase and content of malonaldehyde were the more effective evaluation indexes for evaluating barley salinity tolerance. An appropriate concentration for assessing variability of salt tolerance in seedling growth stage of barley may within the range of150to300mM NaCl concentration in hydroponics and of0.4%to0.6%concentration in potted culture method. Integrated STI showed that the result in two cultural condition were similar based upon factor analysis. The results indicate that Taixing9425, CM72, Sunong6472and Yangsimail were the more tolerant cultivars and Su917112, C2118and Gardner were the more salt sensitive ones.2.150mM NaCl was chosen as the treatment concentration for assessing the variability of the100barley cultivars. The10phenotypic traits including seedling height, root length, leaf age, yellow leaf number, fresh and dry weights of root and stem leaf, the activity of superoxide dismutase(SOD) and content of malonaldehyde (MDA) were investigated. Based on factor analysis, integrated STI (Salt Tolerance Index) of each cultivar was calculated to classify the barley cultivars tested into4different salt-tolerant types:salt tolerance, medium salt tolerance, medium salt susceptible and salt susceptible.51barley cultivars/accessions had the same responses for salt tolerance, including17salt tolerant lines,34medium tolerant,30medium susceptible and19susceptible.3.107pairs of primers in7chromosomes of barley detected323alleles and its range was from2to6with an average of3.02. The polymorphism information content (PIC) value ranged from0.038to0.754with an average of0.408. Genetic distance of tested materials ranged from0.178to0.766with an average of0.507. By NJ cluster and population structure analysis the100accessions were clustered into4main groups. Population analysis based on mixture model clarified the genetic composition of the100accessions,82accessions had a single ancestor relatively and18accessions were from mixed ancestors.4. The proportion of linkage disequulibrium pairs of sites supported by statistical probability (P<0.01) was11.88%in5671combinations of two loci among107SSR primers. However,the percent of combinations with D’>0.5was only3.44%of all combinations.Thirty five loci associated with10traits and11loci associated with more than2traits.25and26loci associated with traits in controled population and treated respectively. The contribution rate of each locus associated with traits ranged from6%to36%. It was revealed that18markers were associated with salt tolerant traits, of which Bmag0013associated with5traits, scssr09398with2traits and the other else with only1trait under salt stress condition. So Bmag0013and scssr09398were preliminarily considered the markers which associated with salt tolerace in barley.