FIELD EVALUATION AND MOLECULAR ANALYSIS OF BEAN GENOTYPES FOR RESISTANCE TO RUST DISEASE

Bean rust, caused by Uromyces appendiculatus (Pers.) Unger, is an important disease in both temperate and tropical bean production regions. Twenty two genotypes of snap bean (Phaseolus vulgaris L.) were collected and screened for resistance to bean rust disease in two seasons. Four genotypes, i.e., Concessa, Hort. 440, Coby and Hana were completely free from infection and were rated as immune to this disease. While, another four genotypes were recorded to disease severity ranged from 1.68% to 3.19% and were categorized as resistant (hypersensitive). Only one genotype was categorized as resistant with disease severity of 9.7%. The remaining 13 genotypes were susceptible having a disease severity ranged from 17.39% to 57.80%. Banding pattern of ten selected genotypes with various levels of resistance and susceptibility to bean rust and genetic diversity among them was evaluated using RAPD, ISSRs and SSRs. The three molecular systems generated total of 75 bands with polymorphism ranged from 60% to 85%. The large number of polymorphic bands allowed easy identification of the different genotypes at the DNA level. The developed dendrogram divided the common bean genotypes into two main clusters. It could be concluded that new promising resources for resistance to leaf rust were recorded in Egyptian snap bean germplasm. In addition, the developed banding patterns for these newly identified valuable Egyptian common bean accessions immune and resistant to leaf rust reported herein could support the future Egyptian snap bean germplasm collection, preservation and utilization.