The rice cultivar Baixiangzhan harbours a recessive gene xa42(t) determining resistance against Xanthomonas oryzae pv. oryzae

Bacterial leaf blight (BB) is among the top 3 diseases in rice production. Breeding resistant cultivars has been the most effective strategy for BB management. The inbred cultivar Baixiangzhan (BXZ) showed a broad spectrum of resistance to five Xoo pathotypes in China, including the prevalent and highly virulent Xoo pathotypes Chinese Race V (CV), which can overcome the resistance of Xa4 and Xa21. The resistance heredity of BXZ has been explored in this study. A single recessive major resistance gene, which designated as xa42(t), confers resistance against the tested Xoo pathotypes CV. Linkage analysis lands xa42(t) on chromosome 6, and genetic mapping confines it to 3.9cM region flanked by RM20558/RM20547 and RM20580. A further seven markers were developed from this interval for high-resolution mapping, and the xa42(t) locus was narrowed to 34.8Kb segment bounded by RM20572 and DT46. The only functionally predicted gene included in the target region is LOC_Os06g45960 if based on the Nipponbare' reference sequence. This candidate gene is predicted to encode a cytochrome P450 protein.