Rice false smut (RFS), caused by Ustilaginoidea virens (Cooke) Takah, is an important fungal disease of rice. In China,sterol demethylation inhibitors (DMIs) are common fungicides used to control RFS. In a previous st...Rice false smut (RFS), caused by Ustilaginoidea virens (Cooke) Takah, is an important fungal disease of rice. In China,sterol demethylation inhibitors (DMIs) are common fungicides used to control RFS. In a previous study, we detectedtwo propiconazole-resistant U. virens isolates in 2015 in Huai’an city, Jiangsu Province, China. In the current study,we detected six propiconazole-resistant isolates out of 180 U. virens isolates collected from rice fields in JiangsuProvince in 2017, and found they were from three different places (Xuzhou, Huai’an and Jintan). All these sixpropiconazole-resistant isolates were cross-resistant to three other sterol demethylation inhibitor (DMI) fungicides, i.e.difenoconazole, tebuconazole, and epoxiconazole. Among them, two isolates (2017–61 and 2017–170) had high fitness.Through sequencing and RT-qPCR analysis, we found that the expression levels of CYP51 and its encoded protein weresignificantly increased in the propiconazole-resistant isolates with a “CC” insertion mutation upstream of the CYP51 codingregion compared to the propiconazole-sensitive isolates. In addition, propiconazole stimulated CYP51 expression in allisolates. Propiconazole also stimulated the accumulation of CYP51 protein in propiconazole-sensitive isolates andpropiconazole-resistant isolates without mutation, but not in propiconazole-resistant isolates with the “CC” mutation.According to JASPAR database analysis, the predicated functional binding sites for propiconazole-resistant isolates with a“CC” insertion mutation and propiconazole-sensitive isolates were different. Given the high fitness of the propiconazoleresistantisolates, the development of resistance to DMIs in U. virens should be monitored. Furthermore, we speculatedthat the over-expression of CYP51 may contribute to DMI resistance in U. virens with the “CC” insertion mutation.展开更多
基金supported by the National Key Research and Development Program of China(2016YFD0300706)the Natural Science Foundation of Jiangsu Province(BK20160588).
文摘Rice false smut (RFS), caused by Ustilaginoidea virens (Cooke) Takah, is an important fungal disease of rice. In China,sterol demethylation inhibitors (DMIs) are common fungicides used to control RFS. In a previous study, we detectedtwo propiconazole-resistant U. virens isolates in 2015 in Huai’an city, Jiangsu Province, China. In the current study,we detected six propiconazole-resistant isolates out of 180 U. virens isolates collected from rice fields in JiangsuProvince in 2017, and found they were from three different places (Xuzhou, Huai’an and Jintan). All these sixpropiconazole-resistant isolates were cross-resistant to three other sterol demethylation inhibitor (DMI) fungicides, i.e.difenoconazole, tebuconazole, and epoxiconazole. Among them, two isolates (2017–61 and 2017–170) had high fitness.Through sequencing and RT-qPCR analysis, we found that the expression levels of CYP51 and its encoded protein weresignificantly increased in the propiconazole-resistant isolates with a “CC” insertion mutation upstream of the CYP51 codingregion compared to the propiconazole-sensitive isolates. In addition, propiconazole stimulated CYP51 expression in allisolates. Propiconazole also stimulated the accumulation of CYP51 protein in propiconazole-sensitive isolates andpropiconazole-resistant isolates without mutation, but not in propiconazole-resistant isolates with the “CC” mutation.According to JASPAR database analysis, the predicated functional binding sites for propiconazole-resistant isolates with a“CC” insertion mutation and propiconazole-sensitive isolates were different. Given the high fitness of the propiconazoleresistantisolates, the development of resistance to DMIs in U. virens should be monitored. Furthermore, we speculatedthat the over-expression of CYP51 may contribute to DMI resistance in U. virens with the “CC” insertion mutation.
