Abstract
Wheat Triticum aestivum L. is one of the most important and strategic crops in the world, which nowadays threatens this important crop to several soil borne fungal diseases, due to climate changes and non-compliance with crop rotation. Common root rot of wheat with a fungal agent Bipolaris sorokiniana is expanding rapidly. Therefore, cultural and breeding methods, especially the use of resistant varieties, can be effective in reducing the disease. In this research, the response of 33 wheat genotypes and lines against this particular disease B. sorokiniana in a greenhouse in the a complete randomized design, and the field in a randomized block design with contamination the field and in greenhouse soil by the related fungus were evaluated during 1395 and 1396, based on 6 severity indexes (0 = asymptomatic, 100 = severe infection resulting the complete plant death). Also, genetic diversity of resistant and susceptible wheat cultivars and lines was performed using SSR marker with seven pairs of Xgwm primers. To investigate the resistance, B. sorokiniana were isolated from infected wheat to common root rot in different parts of wheat fields in Isfahan province. Then, based on morphological and phylogenetic characteristics the isolated were identified as B. sorokiniana and their pathogenicity was confirmed on wheat seedlings “Parsi”. Out of which, a higher pathogenic isolate was selected. Then after reproduction of the B. sorokiniana on sterile wheat grains and infesting the soil in the field and greenhouse, the reaction of wheat cultivars and lines was investigated. The experiments were carried out in three replications in greenhouse, each replicate containing ten wheat plants and in the field with three replications of each replicate in four rows of two meters length. However, to confirm the results of resistant cultivars, these cultivars were repeated four times in greenhouse conditions. Statistical and cluster analysis of data were performed using SAS and SPSS software and comparing the means by Duncan's Multiple Domain Test (DMRT), respectively. The results of greenhouse and field experiment showed that the least level of infection was in Alvand, Bam, M90 and Pishgam genotypes respectively. Alvand with 14.33 and other three cultivars with 24% disease severity. And the highest one was in Back Cross Roshan, Behrang and Zaree with an average of 55.83-55.14 and 55% respectively. Other genotypes were mediated by these two spectra with significant effect.The SSR results showed that 5 pairs of primers produced reciprocal polymorphic bands. The highest and lowest polymorphisms were found to be 0.81 and 0.44 respectively, with an average of 29 to 88% similarity. The cultivars were divided into five main groups