由镰刀菌引起的镰刀菌枯萎病(FHB)是一种严重的真菌病,可以极大地影响小麦的生产。目前,控制主要是通过使用化学杀菌剂来实现的。己康唑(IUPAC名称:2-(2,4-二氯苯基)-1-(1,2,4-三唑-1-基)己-2-醇)是一种广泛使用的三唑类杀菌剂,但该化合物的敏感性尚未确定。目前的研究发现,83个田间分离株的EC50值在0.06和4.33μg/mL之间,平均EC50为0.78μg/mL。对四种抗六唑醇的实验室突变体的评估表明,它们的菌丝生长,与它们的亲本分离株相比,致病性降低,对己唑醇的抗性降低了无性繁殖。同时,突变体似乎对与SDS相关的非生物胁迫更敏感,和H2O2,同时它们对高浓度刚果红的耐受性,Na+和K+增加。分子分析显示FgCYP51靶基因中的许多点突变导致氨基酸取代,包括FgCYP51A中的L92P和N123S,以及M331V,F62L,Q252R,A412V,和V488A在FgCYP51B,还有S28L,S256A,V307A,FgCYP51C中的D287G和R515I,其中三个(S28L,S256A,和V307A)在所有抗性突变体中均保守。此外,发现抗性菌株中FgCYP51基因的表达与其敏感亲本分离株相比显著降低(p<0.05)。发现己康唑与美康唑和氟替诺之间存在正交叉耐药性,以及二芳基胺杀菌剂氟嗪南,但不是丙环唑,和苯吡咯杀菌剂氟二恶英,或者使用戊唑醇,实际上表现出负交叉电阻。这些结果提供了有价值的洞察对三唑类杀菌剂的抗性机制。以及适当选择杀菌剂组合来控制FHB,以确保最佳的小麦产量。
The Fusarium head blight (FHB) caused by Fusarium graminearum is a serious fungal disease that can dramatically impact wheat production. At present, control is mainly achieved by the use of chemical fungicides. Hexaconazole (IUPAC name: 2-(2,4-dichlorophenyl)-1-(1,2,4-triazol-1-yl)hexan-2-ol) is a widely used triazole fungicide, but the sensitivity of F. graminearum to this compound has yet to be established. The current study found that the EC50 values of 83 field isolates of F. graminearum ranged between 0.06 and 4.33 μg/mL, with an average EC50 of 0.78 μg/mL. Assessment of four hexaconazole-resistant laboratory mutants of F. graminearum revealed that their mycelial growth, and pathogenicity were reduced compared to their parental isolates, and that asexual reproduction was reduced by resistance to hexaconazole. Meanwhile, the mutants appeared to be more sensitive to abiotic stress associated with SDS, and H2O2, while their tolerance of high concentration of Congo red, and Na+ and K+ increased. Molecular analysis revealed numerous point mutations in the FgCYP51 target genes that resulted in amino acid substitutions, including L92P and N123S in FgCYP51A, as well as M331V, F62L, Q252R, A412V, and V488A in FgCYP51B, and S28L, S256A, V307A, D287G and R515I in FgCYP51C, three of which (S28L, S256A, and V307A) were conserved in all of the resistant mutants. Furthermore, the expression of the FgCYP51 genes in resistant strains was found to be significantly (p < 0.05) reduced compared to their sensitive parental isolates. Positive cross-resistance was found between hexaconazole and metconazole and flutriafol, as well as with the diarylamine fungicide fluazinam, but not with propiconazole, and the phenylpyrrole fungicide fludioxonil, or with tebuconazole, which actually exhibited negative cross-resistance. These results provide valuable insight into resistant mechanisms to triazole fungicides in F. graminearum, as well as the appropriate selection of fungicide combinations for the control of FHB to ensure optimal wheat production.