Rice blast caused by Magnaporthe oryzae is one of the most devastating disease causing major yield losses worldwide in every year. Use of resistant rice varieties is one of the most effective ways to control the disease and reduce yield loss. Molecular screening and allelic diversity of major rice blast resistant genes were determined in forty-eight (48) genotypes of rice germplasms of Bangladesh with ten (10) previously synthesized gene based SSR (Single Sequence Repeats) markers [RM 541, RM 224, RM21, RM527, RM 208, RM 247,RM 72, RM 259, RM 246 & RM 206]. The genetic frequencies of ten (10) major blast resistance genes (Pi-9, Pi-1, Pi-5(t), Piz-5, Pi-b, Pi-b, Pi-ta, Pi-33, Pi27(t), Pitp(t) and Pi-kh) were ranged from 2% to 93%. The blast resistance gene Pi-kh was widely (93%) and Pi5 (2%) was sparsely distributed among the studied genotypes. Nine (9) genotypes sonaanjana, jabedshail, karaja, pajon, IR-09, BAU 39, binni, katiabagdad and kataribhug, had maximum eight (8) blast resistance genes and only one BRRIdhan 46 had minimum two (2) blast resistance genes. Twelve genotypes possessed seven, twelve had six, seven had five and five had four resistant genes. Out of forty-eight (48) genotypes, forty-five (45) genotypes occupied at least five (5) positive fragments of expected product size. Allelic diversity was also found among the rice genotypes for different blast resistance genes.
Key words: Rice, blast, resistance genes, SSR markers
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