Abstract
Evaluation of genetic diversity in plant germplasms is the first and fundamental step in plant breeding programs. For the fact that correct usage of it has lots of benefits, it decreases plants’ damage associated with pests and diseases. In this study, genetic diversity and relationship of 70 genotypes of bread wheat were evaluated by using 60 microsatellite markers. 40 polymorphic markers were selected for clustering and evaluating of genotypes. In total, 309 polymorphic alleles were amplified with an average of 9.26 allele per microsatellite locus. Gene diversity according to Nei for the 42 microsatellite loci varied from 0.4 to 0.91 with an average of 0.74. Polymorphism information content (PIC) value ranged from 0.365 for the barc 87 and the second locus of barc 165 to 0.902 for theXgwm213, with an average of 0.688. Clustering analyses based on Neibour-joinig algorithms and distance coefficient was used and all of the dendrograms indicated that most relative genotypes based on pedigree information, were grouped in the same cluster. In general, they could separate Bolani and MV17 genotypes that are susceptible and resistant parents in most rust breeding projects in the country. The dendrogram result of Rogers distance showed high concordance with available pedigree information of genotypes. Principle components analysis (PCA) also indicates similar results. With stepwise multivariate regression analysis according to the reactions of genotypes to yellow rust and their molecular result, 19 and 17 informative markers were detected for final infection coefficient and area under disease progress curve, respectively. Key words: Bread wheat (Triticum aestivum), microsatellite markers, genetic diversity, yellow rust.
Highlights
Common wheat (Triticum aestivum) (2n = 6x = 42) is the most diverse and important specie of the plant, which produces large edible grain and provides about onefourth of humans’ food calories and a large part of their nutrient requirements
Before ANOVA, Log-normal distribution was used for standardizing of data, data were analyzed based on completely randomized blocks design and the results displayed that significant difference there was among the genotypes in terms of response to disease
Wei et al (2005), Huang et al (2002) and Manifesto et al (2001) assessed genetic diversity of wheat genotypes originating from different countries with simple sequence repeats (SSR) markers and reported a variation in allele number per locus and gene diversity almost similar to that revealed in this study
Summary
One of the substantial diseases is yellow rust or stripe rust that is caused by Puccinia striiformis Tritici which adapts to cool and humid weather (Eversmeyer and Kramer, 2000; Ma and Singh, 1996). Stripe rust is much more important than leaf rust or stem rust, because, in severe infection with the pathogen, the plant height, the number of seeds accompanied by their quality and weight, are decreased (Ma and Singh, 1996); so, current disease situations, plant pathologists, breeders, farmers, and governmental organizations have given much attention to the research on, and control of it (Kang et al, 2010). With attention to the role of yellow rust disease in reducing wheat yield, finding appropriate parents and detecting the loci of resistance genes and transferring them to produce resistant varieties are the best strategies to control the disease.
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