Evaluation of resistance genes in rice against local isolates of Xanthomonas oryzae pv. oryzae in Punjab Province of Pakistan

Abstract

Absence of resistance/tolerance against bacterial leaf blight (BLB), incited by Xanthomonas oryzae pv. oryzae, in famous basmati varieties is one of the main reason for BLB epidemic in Punjab in 2007–2008. For developing resistance against BLB, the response of 26 IRBB lines of IRRI including 10 near isogenic lines (NILs) and 16 gene pyramids carrying two to five resistance genes (Xa series) was evaluated against 61 indigenous Xoo isolates under artificial inoculation field conditions. None of the NILs or gene pyramid provides complete protection against all the isolates. However, Xa21 and xa13 were found resistant against the majority of Xoo isolates, followed by Xa14 and Xa7. Of the 16 gene pyramids used in this study, IRBB-54 (Xa5 + Xa21), IRBB-55 (Xa13 + Xa21) followed by IRBB-58 (Xa4 + Xa13 + Xa21) were found effective against the majority of the Xoo isolates. These resistance genes (individually and in combinations) can be incorporated for the improvement of basmati rice cultivars cultivated in Punjab province of Pakistan. Effectiveness of gene combination supports the strategy of pyramiding appropriate resistance genes. Newly identified resistant genes may also be evaluated for achieving broad spectrum resistance against more Xoo isolates of the area.