Cox Kerik D, Quello Kacie, Deford Ryan J, Beckerman Janna L
Department of Plant Pathology and Plant-Microbe Biology, Barton Laboratory, New York State Agricultural Experiment Station, Cornell University, Geneva 14456.
Department of Botany and Plant Pathology, Purdue University, West Lafayette 47907.
Plant Dis. 2009 Apr;93(4):328-331. doi: 10.1094/PDIS-93-4-0328.
Management of brown rot of stone fruit relies upon the application of effective fungicides that may be compromised by the development of fungicide resistance. We evaluated fungicide resistance in the brown rot pathogen, Monilinia fructicola, using Alamar blue (AB) dye, or resazurin, a chromogenic substrate that can be used as an indicator of respiration, in a 96-well microtiter format. We compared the AB method to traditional mycelial growth assays for resistance screening using 10 isolates of M. fructicola that represented a range of sensitivities to fenbuconazole. Using traditional mycelial growth assays, isolate sensitivity ranged from 17.7 to 115.3% growth on medium amended with fenbuconazole at 0.03 μg/ml relative to that on nonamended medium. Concordant results between both assays were obtained (R = 0.9943, P < 0.0001), but the AB method provided results within 24 h, as opposed to the 3- to 5-day period required for mycelial growth assays. We found that sensitive isolates reduced AB less than resistant isolates in the presence of fungicide. Spore density influenced the reduction of AB by M. fructicola; spectrophotometric discrimination of fungicide sensitivity was best achieved at a density of 10 spores/ml.
核果褐腐病的防治依赖于施用有效的杀菌剂，但杀菌剂抗性的发展可能会削弱其效果。我们使用阿拉玛蓝（AB）染料或刃天青（一种可作为呼吸指示剂的显色底物），以96孔微量滴定板形式评估了褐腐病菌（果生链核盘菌）对杀菌剂的抗性。我们将AB法与传统的菌丝生长测定法进行了比较，以筛选对苯醚甲环唑具有不同敏感性的10株果生链核盘菌的抗性。使用传统的菌丝生长测定法，相对于未添加苯醚甲环唑的培养基，在添加了0.03μg/ml苯醚甲环唑的培养基上，分离株的生长敏感性范围为17.7%至115.3%。两种测定方法获得了一致的结果（R = 0.9943，P < 0.0001），但AB法在24小时内即可得出结果，而菌丝生长测定法则需要3至5天。我们发现，在存在杀菌剂的情况下，敏感分离株比抗性分离株对AB的还原作用更小。孢子密度影响了果生链核盘菌对AB的还原作用；在孢子密度为10个孢子/ml时，通过分光光度法区分杀菌剂敏感性的效果最佳。
