Rice false smut (RFS), an emerging major fungal disease worldwide caused by Ustilaginoidea virens, affects rice grain quality and yield. RFS cause 2.8–49% global yield loss depending upon disease severity and cultivars. In India, the yield loss due to RFS ranged from 2 to 75%. Identification of the genes or quantitative trait loci (QTLs) governing disease resistance would be of utmost importance towards mitigating the economic losses incurred due to RFS. Here, we report mapping of RFS resistance QTLs from a resistant breeding line RYT2668. The mapping population was evaluated for RFS resistance under the field condition in three cropping seasons 2013, 2015, and 2016. A positive correlation among infected panicle/plant, total smut ball/panicle, and disease score was observed in the years 2013, 2015, and the mean data. A total of seven QTLs were mapped on rice chromosomes 2, 4, 5, 7, and 9 using 2326 single nucleotide polymorphism markers. Of these, two QTLs, qRFSr5.3 and qRFSr7.1a, were associated with the infected panicle per plant, one QTL qRFsr9.1 with total smut ball per panicle, and four QTLs qRFSr2.2, qRFSr4.3, qRFSr5.4, and qRFSr7.1b with disease score. Among them, a novel QTL qRFSr9.1 on chromosome 9 exhibits the largest phenotypic effect. The prediction of putative candidate genes within the qRFSr9.1 revealed four nucleotide-binding sites–leucine-rich repeat (NBS-LRR) domain-containing disease resistance proteins. In summary, our findings mark the hotspot region of rice chromosomes carrying genes/QTLs for resistance to the RFS disease.

水稻假黑穗病（RFS），一种由黑粉虱引起的全球新出现的主要真菌病害，影响稻谷品质和产量。RFS 导致全球产量损失 2.8-49%，具体取决于疾病严重程度和品种。在印度，RFS 导致的产量损失在 2% 到 75% 之间。鉴定控制抗病性的基因或数量性状位点 (QTL) 对于减轻 RFS 造成的经济损失至关重要。在这里，我们报告了来自抗性育种系 RYT2668 的 RFS 抗性 QTL 的定位。在 2013 年、2015 年和 2016 年三个种植季节，在田间条件下对绘图种群的 RFS 抗性进行了评估。在 2013 年、2015 年观察到受感染的穗/株、黑穗病球/穗总数和疾病评分之间呈正相关，和平均数据。使用2326个单核苷酸多态性标记，在水稻第2、4、5、7和9号染色体上共定位了7个QTL。qRFSr5.3和qRFSr7.1a与每株受感染的圆锥花序相关，一个 QTL qRFsr9.1与每个圆锥花序总黑穗病球有关，四个 QTL qRFSr2.2、qRFSr4.3、qRFSr5.4和qRFSr7.1b与疾病相关分数。其中，9号染色体上的新型QTL qRFSr9.1表现出最大的表型效应。qRFSr9.1内推定的候选基因的预测揭示了四个核苷酸结合位点 - 富含亮氨酸重复 (NBS-LRR) 结构域的抗病蛋白。总之，我们的研究结果标记了携带抗RFS病基因/QTL的水稻染色体的热点区域。