Identification and fine-mapping of quantitative trait loci (QTL) conferring rice false smut resistance in rice.

Rice false smut(RFS)is a rice fungal disease caused by the bio-trophic fungus Ustilaginoidea virens(Cooke)Takahashi.The patho-genic fungus specifically infects rice spikelets at the booting stage and coverts the infected spikelets into false smut balls consisting of hyphae and chlamydospores(Ashizawa et al.,2012;Sun et al.,2020).RFS not only causes yield loss of rice,but also produces various kinds of toxins like ustiloxins and ustilaginoidins,which are highly poisonous to human and livestock,posing a threat to food se-curity and human health(Hu et al.,2020;Sun et al.,2022).In recent years,RFS is emerging as a major disease of rice worldwide,mainly due to the cultivation of high-yield hybrid rice(super rice)cultivars,increasing use of nitrogen fertilizers,and climate change(Brooks et al.,2009;Mohiddin et al.,2012;Sun et al.,2020).Currently,most rice cultivars grown in China are susceptible to false smut.Manage-ment of the disease mainly depends on chemical fungicides(Liang et al.,2014).However,heavy use of fungicides can cause environ-mental pollution and facilitate the emergence of fungicide resistance in the pathogenic fungus.Therefore,breeding rice cultivars with a high level of RFS resistance is an effective and environmentally-friendly way to control the disease,which requires identification and isolation of resistance genes or quantitative trait loci(QTL)for RFS in rice accession collection(Ge et al.,2022;Zhao et al.,2022).