Standish J R, Tomaso-Peterson M, Allen T W, Sabanadzovic S, Aboughanem-Sabanadzovic N
Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State 39762.
Delta Research and Extension Center, Mississippi State University, Stoneville 38776.
Plant Dis. 2015 Oct;99(10):1347-1352. doi: 10.1094/PDIS-02-15-0157-RE. Epub 2015 Aug 20.
Frogeye leaf spot, caused by Cercospora sojina Hara, is a foliar disease affecting soybean (Glycine max (L.) Merr.), often managed by applications of quinone outside inhibitor (QoI) fungicides. In 2013 and 2014, 634 C. sojina monoconidial isolates were collected from soybean fields throughout Mississippi. Initially, in vitro bioassays were performed to evaluate the sensitivity of 14 of 634 isolates plus a baseline. Resistant and sensitive isolates were characterized by determining the effective fungicide concentrations at which 50% of conidial germination was inhibited (EC). The molecular mechanism of resistance was determined for all 634 isolates, using a PCR-RFLP method and comparing nucleotide sequences of the cytochrome b gene. The state of Mississippi was divided into five distinct geographical regions (the Hills, Delta, Pines, Capital, and Coast) based on estimates of total soybean hectares. The greatest proportion (16.7%) of QoI-sensitive isolates was collected in the Hills while the Coast had no QoI-sensitive isolates. QoI-sensitive isolates from the Pines, Capital, and Delta ranged from 1.6 to 7.0%. Results of this study determined that more than 93% of C. sojina isolates collected in Mississippi carried the G143A amino acid substitution, indicating a shift to a QoI-resistant population throughout Mississippi soybean fields.
由大豆尾孢菌（Cercospora sojina Hara）引起的蛙眼叶斑病是一种影响大豆（Glycine max (L.) Merr.）的叶部病害，通常通过施用醌外抑制剂（QoI）类杀菌剂进行防治。2013年和2014年，从密西西比州各地的大豆田采集了634个大豆尾孢菌单孢分离株。最初，进行了体外生物测定，以评估634个分离株中的14个以及一个基线的敏感性。通过确定抑制50%分生孢子萌发的有效杀菌剂浓度（EC）来表征抗性和敏感分离株。使用PCR-RFLP方法并比较细胞色素b基因的核苷酸序列，确定了所有634个分离株的抗性分子机制。根据大豆总公顷数的估计，将密西西比州划分为五个不同的地理区域（山区、三角洲、松林、首府区和海岸区）。山区采集到的QoI敏感分离株比例最高（16.7%），而海岸区没有QoI敏感分离株。来自松林、首府区和三角洲的QoI敏感分离株比例在1.6%至7.0%之间。本研究结果确定，在密西西比州采集的超过93%的大豆尾孢菌分离株携带G143A氨基酸替换，表明整个密西西比州大豆田的病原菌群体已转变为对QoI抗性群体。
