Among rice (Oryza sativa L.) bacterial leaf blight (BB), which is caused by Xanthomonas oryzae pv. oryzae, plays a pivotal role in decreasing rice yield. It is reported to be the most serious constraint to improving rice yield. The present investigation assessed the potentiality of BB resistance and molecular characterization of 100 rice accessions for four major BB resistance genes, viz., Xa4, xa5, xa13, and Xa21. Disease screening was carried out under glasshouse conditions using a BB culture isolated from BB-infected rice fields through the leaf clipping method. Analyses of 13 BB resistance genes linked with polymorphic microsatellites markers indicated the presence of single-, two-, three-, and four-gene combinations of xa5, xa13, Xa4, and Xa21. We found four accessions to be resistant, 34 accessions to be moderately resistant, 49 accessions to be moderately susceptible, and 13 accessions to be susceptible. Among the resistant lines, IR12L110, Namcheonbyeo, Dhalaheera, and SahbhagiDhan recorded a minimum lesion length of 3.70, 4.20, 4.67, and 8.30 cm, respectively. Phylogenetic tree, constructed using molecular data, grouped the rice germplasm into four major clusters. Resistant genes xa5 and Xa4 contributed 14 positive compatible resistant genes, each belonging to 28 germplasm for the BB resistance. The potential genetic resources identified as resistant to the BB can be used as donors for the improvement of rice bacterial blight resistance in rice breeding programs.

在水稻 ( Oryza sativa L.) 中，细菌性叶枯病 (BB) 是由Xanthomonas oryzae pv引起的。oryzae，在降低水稻产量中起着举足轻重的作用。据报道，这是提高水稻产量的最严重制约因素。本研究评估了 100 个水稻品种的 BB 抗性潜力和四种主要 BB 抗性基因的分子特征，即Xa4、xa5、xa13和Xa21. 病害筛查是在温室条件下使用通过剪叶法从受 BB 感染的稻田中分离的 BB 培养物进行的。对与多态性微卫星标记连锁的 13 个 BB 抗性基因的分析表明存在xa5、xa13、Xa4和Xa21的单、二、三和四基因组合。我们发现 4 个材料抗性，34 个材料中等抗性，49 个材料中等敏感，13 个材料敏感。在抗性品系中，IR12L110、Namcheonbyeo、Dhalaheera 和 SahbhagiDhan 记录的最小病斑长度分别为 3.70、4.20、4.67 和 8.30 cm。使用分子数据构建的系统发育树将水稻种质分为四大类。抗性基因xa5和Xa4贡献了 14 个阳性相容抗性基因，每个基因属于 28 个 BB 抗性种质。被鉴定为对 BB 具有抗性的潜在遗传资源可用作在水稻育种计划中改善水稻白叶枯病抗性的捐助者。