Abstract：
This study characterized 52 isolates of Monilinia fructicola from peach and nectarine orchards for their multi-resistance patterns to thiophanate-methyl (TF), tebuconazole (TEB), and azoxystrobin (AZO) using in vitro sensitivity assays and molecular analysis. The radial growth of M. fructicola isolates was measured on media amended with a single discriminatory dose of 1 µg/ml for TF and AZO and 0.3 µg/ml for TEB. Cyt b, CYP51, and ß-tubulin were tested for point mutations that confer resistance to quinone outside inhibitors (QoIs), demethylation inhibitors (DMIs), and methyl benzimidazole carbamates (MBCs), respectively. Eight phenotypes were identified including isolates with single, double, and triple in vitro resistance to QoI, MBC, and DMI fungicides. All resistant phenotypes to TF and TEB presented the H6Y mutation in ß-tubulin and the G641S mutation in CYP51. None of the point mutations typically linked to QoI resistance were present in the Monilinia isolates examined. Moreover, fitness of the M. fructicola phenotypes was examined in vitro and detached fruit assays. Phenotypes with single-resistance displayed equal fitness in in vitro and fruit assays compared to the wild-type. In contrast, the dual and triple-resistance phenotypes suffered fitness penalties based on osmotic sensitivity and aggressiveness on peach fruit. In this study, multiple resistance to MBC, DMI, and QoI fungicide groups was confirmed in M. fructicola. Results suggest that Monilinia populations with multiple resistance phenotypes are likely to be less competitive in the field than those with single resistance, thereby impeding their establishment over time and facilitating disease management.
摘要：
这项研究鉴定了来自桃和油桃果园的52种分离株对甲基托布津（TF）的多重抗性模式，戊唑醇(TEB),使用体外敏感性测定和分子分析和偶氮酯（AZO）。在TF和AZO的单一区分剂量为1µg/ml，TEB的单一区分剂量为0.3µg/ml的培养基上测量果果支原体分离株的径向生长。Cytb,CYP51和β-微管蛋白进行了点突变测试，这些点突变赋予对醌外部抑制剂（QoIs）的抗性，去甲基化抑制剂（DMIs），和甲基苯并咪唑氨基甲酸酯（MBCs），分别。鉴定了8种表型，包括具有单一，双,对QoI的体外抗性是三倍，MBC,和MDI杀菌剂。TF和TEB的所有抗性表型在β-微管蛋白中呈现H6Y突变，在CYP51中呈现G641S突变。通常与QoI抗性相关的点突变均不存在于所检查的Monilinia分离株中。此外，在体外和分离的果实试验中检查了果聚糖表型的适应性。与野生型相比，具有单抗性的表型在体外和水果测定中显示出相等的适应性。相比之下,基于渗透敏感性和对桃子果实的侵袭性，双重和三重抗性表型遭受了适应性惩罚。在这项研究中,对MBC的多重抗性，QI,和QoI杀真菌剂组在果蝇中得到证实。结果表明，具有多种抗性表型的Monilinia种群在该领域的竞争力可能低于具有单一抗性的种群，从而阻碍它们随着时间的推移而建立并促进疾病管理。
