Genetic profiling of bacterial leaf blight resistance genes in Bangladeshi rice varieties

Although bacterial leaf blight (BLB) poses a threat to rice yields in Bangladesh, locally validated resistance profiles are limited. This study addresses this gap by identifying key resistance genes and evaluating their distribution in widely cultivated rice varieties in the Mymensingh region of Bangladesh. This study aimed to identify bacterial leaf blight resistance genes (Xa4, Xa5, Xa7, Xa13, and Xa21) present in rice varieties cultivated in Mymensingh, a prominent rice-producing region in Bangladesh.

We genotyped symptomatic leaves (n = 187) from 10 varieties at 14 locations in Mymensingh using diagnostic markers for Xa4, Xa5, Xa7, xXa13, and Xa21; selected amplicons were Sanger-sequenced and analyzed (NJ trees, 1,000 bootstraps).

The results revealed distinct resistance gene profiles: BRRI Dhan-49 presented the recessive gene Xa13; BRRI Dhan-51 possessed multiple resistance genes ( Xa2, Xa7, and Xa5); and BRRI Dhan-34 contained the Xa4, Xa5, and Xa7 genes. Compared with single-gene varieties, varieties characterized by different resistance genes demonstrated superior protection against bacterial blight, outperforming. Phylogenetic analyses revealed that the Bangladeshi varieties exhibit a close genetic relationship, reflecting a localized breeding history and adaptation, which distinguishes them from other international rice varieties.

Multi-gene varieties (BRRI Dhan-51, Dhan-34) offer stronger field protection than single-gene materials, supporting gene pyramiding and germplasm diversification for durable BLB resistance in Bangladesh.