Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598.
University of Tennessee Institute of Agriculture, Knoxville, TN 37996.
Plant Dis. 2022 Apr;106(4):1203-1208. doi: 10.1094/PDIS-08-21-1658-RE. Epub 2022 Mar 27.
and . cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were to determine the sensitivity of . and . isolates from strawberry to azoxystrobin and to investigate mechanisms of quinone-outside-inhibitor resistance present in . and . based on the known point mutations within the () gene. Isolates of both spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 μg/ml on potato dextrose agar amended with salicylhydroxamic acid (100 μg/ml). Isolates were separated into two groups - sensitive isolates with the 50% effective concentration () values <1.0 μg/ml, and resistant isolates having values >50 μg/ml. . and . resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant . isolates. However, in . , qualitative resistance was observed, but the isolates lacked all the known mutations in the gene. This is the first report of resistance to azoxystrobin in . and . .
和。引起果实皮革腐烂（LR）和草莓疫霉冠腐（PhCR）。LR 发生具有间歇性，但在天气有利时可导致高达 70%的果实损失。在佛罗里达州的草莓冬季年度生产系统中，PhCR 可能很严重，导致植物矮化、死亡和严重的产量损失。嘧菌酯已被标记用于防治 LR，但不能防治 PhCR。本研究的目的是确定来自草莓的和。对嘧菌酯的敏感性，以及基于已知的（）基因内的点突变，调查存在于和。醌外抑制剂抗性的机制。引起 LR 和 PhCR 的两种 spp。分离物于 1997 年至 2020 年期间从佛罗里达州的多个草莓田采集。在添加水杨羟肟酸（100 μg/ml）的马铃薯葡萄糖琼脂上，在 0、0.01、0.1、1.0、10 和 50 μg/ml 下测试分离物对嘧菌酯的敏感性。分离物分为两组 - 对嘧菌酯敏感的分离物的 50%有效浓度（）值<1.0 μg/ml，而抗性分离物的值>50 μg/ml。发现 2010 年后采集的分离物对嘧菌酯具有抗性。从两种物种的敏感和抗性分离物中选择，对线粒体 基因的前 450 个核苷酸进行测序。报道对嘧菌酯具有抗性的 G143A 突变存在于所有抗性。分离株。然而，在。中，观察到定性抗性，但分离株缺乏基因中所有已知的突变。这是首次报道对嘧菌酯的抗性。和。。
