Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod 123, Oman.
Plant Dis. 2018 Jan;102(1):202-208. doi: 10.1094/PDIS-11-16-1680-RE. Epub 2017 Oct 23.
A study was conducted to characterize the common Pythium spp. in greenhouses in Oman and their level of resistance to hymexazol, a widely used fungicide in the country. Pythium isolates were obtained from soil samples, cocopeat bags, and cucumber roots collected from seven regions in the country. Identification of 80 Pythium isolates to the species level using sequences of the internal transcribed spacer region of the ribosomal RNA showed that they belong to four species: Pythium aphanidermatum (77 isolates), P. spinosum (1 isolate), P. myriotylum (1 isolate), and P. catenulatum (1 isolate). Investigating the aggressiveness of three Pythium spp. on cucumber showed that P. aphanidermatum, P. myriotylum, and P. spinosum are pathogenic. Phylogenetic analysis of P. aphanidermatum isolates showed that most of the isolates obtained from cocopeat clustered separately from isolates obtained from soil and roots. This may indicate a difference in the origin of the cocopeat isolates. Evaluating the resistance of 27 P. aphanidermatum isolates to hymexazol showed that most isolates were sensitive (0.9 to 31.2 mg liter) whereas one isolate was resistant (142.9 mg liter). This study is the first to report P. myriotylum and P. catenulatum in Oman. It is also the first to report the development of resistance to hymexazol among P. aphanidermatum populations from greenhouses. Growers should use integrated disease management strategies to avoid further development of resistance to hymexazol.
一项研究旨在描述阿曼温室中常见的 Pythium spp.及其对 hymexazol 的抗性水平，hymexazol 是该国广泛使用的一种杀菌剂。从该国七个地区采集的土壤样本、椰糠袋和黄瓜根中获得了 Pythium 分离株。使用核糖体 RNA 内部转录间隔区的序列对 80 个 Pythium 分离株进行鉴定，结果表明它们属于四个物种：腐霉（Pythium aphanidermatum）（77 个分离株）、棘腐霉（P. spinosum）（1 个分离株）、少根腐霉（P. myriotylum）（1 个分离株）和旋毛腐霉（P. catenulatum）（1 个分离株）。研究三种 Pythium spp.对黄瓜的侵袭性表明，腐霉、少根腐霉和棘腐霉是致病的。腐霉分离株的系统发育分析表明，从椰糠中获得的大多数分离株与从土壤和根部获得的分离株分开聚类。这可能表明椰糠分离株的来源不同。评估 27 个腐霉分离株对 hymexazol 的抗性表明，大多数分离株敏感（0.9 至 31.2 mg/L），而一个分离株耐药（142.9 mg/L）。本研究首次在阿曼报道了少根腐霉和旋毛腐霉。这也是首次报道温室中腐霉种群对 hymexazol 产生抗性。种植者应使用综合疾病管理策略，以避免 hymexazol 抗性的进一步发展。
