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Shrestha BK, Ward BM, Allen TW, da Silva ET, Zulli H, Dunford W, Doyle V, Bradley CA, Buckley B, Chen P, Clubb M, Kelly H, Koebernick J, Padgett B, Rupe JC, Sikora EJ, Spurlock TN, Thomas-Sharma S, Tolbert A, Zhou XG, Price PP. Characterization of QoI-Fungicide Resistance in Cercospora Isolates Associated with Cercospora Leaf Blight of Soybean from the Southern United States. PLANT DISEASE 2024; 108:149-161. [PMID: 37578368 DOI: 10.1094/pdis-03-23-0588-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Cercospora leaf blight (CLB) of soybean, caused by Cercospora cf. flagellaris, C. kikuchii, and C. cf. sigesbeckiae, is an economically important disease in the southern United States. Cultivar resistance to CLB is inconsistent; therefore, fungicides in the quinone outside inhibitor (QoI) class have been relied on to manage the disease. Approximately 620 isolates from plants exhibiting CLB were collected between 2018 and 2021 from 19 locations in eight southern states. A novel polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay based on two genes, calmodulin and histone h3, was developed to differentiate between the dominant species of Cercospora, C. cf. flagellaris, and C. cf. sigesbeckiae. A multilocus phylogenetic analysis of actin, calmodulin, histone h3, ITS rDNA, and transcription elongation factor 1-α was used to confirm PCR-RFLP results and identify remaining isolates. Approximately 80% of the isolates collected were identified as C. cf. flagellaris, while 15% classified as C. cf. sigesbeckiae, 2% as C. kikuchii, and 3% as previously unreported Cercospora species associated with CLB in the United States. PCR-RFLP of cytochrome b (cytb) identified QoI-resistance conferred by the G143A substitution. Approximately 64 to 83% of isolates were determined to be QoI-resistant, and all contained the G143A substitution. Results of discriminatory dose assays using azoxystrobin (1 ppm) were 100% consistent with PCR-RFLP results. To our knowledge, this constitutes the first report of QoI resistance in CLB pathogen populations from Alabama, Arkansas, Kentucky, Mississippi, Missouri, Tennessee, and Texas. In areas where high frequencies of resistance have been identified, QoI fungicides should be avoided, and fungicide products with alternative modes-of-action should be utilized in the absence of CLB-resistant soybean cultivars.
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Affiliation(s)
| | - Brian M Ward
- Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, LA
| | - Tom W Allen
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS
| | - Ernesto T da Silva
- Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, LA
| | - Hannah Zulli
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA
| | - Will Dunford
- Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, LA
| | - Vinson Doyle
- Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, LA
| | - Carl A Bradley
- Department of Plant Pathology, University of Kentucky, Princeton, KY
| | - Blair Buckley
- Red River Research Station, LSU AgCenter, Bossier, LA
| | - Pengyin Chen
- Fisher Delta Research Center, University of Missouri, Portageville, MO
| | - Michael Clubb
- Fisher Delta Research Center, University of Missouri, Portageville, MO
| | - Heather Kelly
- West Tennessee Research and Education Center, University of Tennessee, Jackson, TN
| | - Jenny Koebernick
- Department of Crop, Soil, and Environmental Science, Auburn University, Auburn, AL
| | - Boyd Padgett
- Dean Lee Research and Extension Center, LSU AgCenter, Alexandria, LA
| | - John C Rupe
- Department of Crop, Soil, and Environmental Science, University of Arkansas, Fayetteville, AR
| | - Ed J Sikora
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL
| | - Terry N Spurlock
- Department of Crop, Soil, and Environmental Science, University of Arkansas, Fayetteville, AR
| | - Sara Thomas-Sharma
- Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, LA
| | - Amanda Tolbert
- Department of Crop, Soil, and Environmental Science, University of Arkansas, Fayetteville, AR
| | - Xin-Gen Zhou
- Research and Extension Center, Texas A&M University, Beaumont, TX
| | - Paul P Price
- Macon Ridge Research Station, LSU AgCenter, Winnsboro, LA
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Yu X, Zhang J, Zhang X, Yang X, Xu X, Lin J, Bing H, Wang X, Zhao J, Xiang W. Identification and Pathogenicity of Fungi Associated with Leaf Spot of Muskmelon in Eastern Shandong Province, China. PLANT DISEASE 2022; 106:872-890. [PMID: 34645310 DOI: 10.1094/pdis-06-21-1126-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Leaf spot is a serious disease in the growth and development of muskmelon, which can affect its quality and yield. Over the past years, Malianzhuang Muskmelon Base, the main muskmelon producing area in Shandong Province, China, has been seriously affected by leaf spot. Since 2018, symptomatic leaves were collected from 11 production areas of this base to determine the pathogens of muskmelon foliar diseases. Two-hundred fungal strains were isolated and 10 genera and 17 species were identified based on morphological characteristics and multilocus phylogenetic analysis (ITS, GADPH, RPB2, HIS3, EF-1α, and LSU). The most frequently isolated species from each sampling area was Alternaria tenuissima with 77 strains, followed by A. alternata. Pathogenicity experiments showed that A. alternata, A. tenuissima, Fusarium neocosmosporiellum (formerly Neocosmospora vasinfecta), F. acuminatum, Exserohilum rostratum, Bipolaris sorokiniana, and Stagonosporopsis cucurbitacearum (formerly Didymella bryoniae) could cause symptoms highly similar to those of infected leaves observed under natural conditions in the field. Therefore, these fungal isolates are considered to be the primary pathogens causing muskmelon leaf spot, and A. tenuissima and A. alternata were the most common and virulent pathogens in this study. In addition, this is the first study of F. neocosmosporiellum, F. acuminatum, E. rostratum, and B. sorokiniana as pathogens associated to muskmelon leaf spot in China as well as the world.
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Affiliation(s)
- Xiaoyan Yu
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Jing Zhang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Xue Zhang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Xilang Yang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Xi Xu
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Jiaying Lin
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Hui Bing
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Xiangjing Wang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Junwei Zhao
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
| | - Wensheng Xiang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, Northeast Agricultural University, Harbin 150030, P.R. China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, P.R. China
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