Assessing high-yielding cowpea varieties for bacterial blight resistance in Bangladesh: A step towards an...

Cowpea is well-known worldwide for its high protein content, versatile use, and adaptability. However, it is devastatingly affected by bacterial blight disease caused by Xanthomonas axonopodis pv. vignicola (Xav). The present study was designed to assess ten high-yielding cowpea varieties for bacterial blight resistance in two contrasting cropping seasons in Bangladesh. The varieties were evaluated using seed and stem inoculation with Xav bacteria, followed by phenotypic and molecular characterisation. The varieties were morphologically assessed using nine disease-related qualitative and quantitative traits, and genetic variations were investigated through nine SSR markers. Disease development varied significantly (P = 0.05) among the varieties. Substantially higher disease incidence was observed in the Kharif season compared to the Rabi season. Felon local, Dark Green-28, and Dark Green-1028 varieties were resistant in both seasons. On the other hand, BARI Felon-1 was highly susceptible to susceptible in both seasons as infections were over 50%. Moreover, plant height, leaf area, branch number, and leaf number significantly differed among the varieties. Besides, in the molecular study, polymorphism information content and Nei's gene diversity were detected as 0.3658 and 0.4089, respectively. Kegornatki showed the highest genetic variation vs Dark Green-1028. The UPGMA dendrogram segregated the ten cowpea varieties into two main clusters. This study revealed that three high-yielding varieties, viz., Dark Green-28, Dark green 1028, and Felon local, were resistant to bacterial blight and showed better performance in morpho-molecular characterisation. Therefore, these varieties can be integrated into future cowpea breeding programmes to develop cultivars that can control the high pressures of Xav.