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Lambert C, Schweizer L, Matio Kemkuignou B, Anoumedem EGM, Kouam SF, Marin-Felix Y. Four new endophytic species of Diaporthe (Diaporthaceae, Diaporthales) isolated from Cameroon. MycoKeys 2023; 99:319-362. [PMID: 37915461 PMCID: PMC10616871 DOI: 10.3897/mycokeys.99.110043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 09/26/2023] [Indexed: 11/03/2023] Open
Abstract
The genus Diaporthe (Diaporthaceae, Diaporthales) is a large group of fungi frequently reported as phytopathogens, with ubiquitous distribution across the globe. Diaporthe have traditionally been characterized by the morphology of their ana- and teleomorphic state, revealing a high degree of heterogeneity as soon as DNA sequencing was utilized across the different members of the group. Their relevance for biotechnology and agriculture attracts the attention of taxonomists and natural product chemists alike in context of plant protection and exploitation for their potential to produce bioactive secondary metabolites. While more than 1000 species are described to date, Africa, as a natural habitat, has so far been under-sampled. Several endophytic fungi belonging to Diaporthe were isolated from different plant hosts in Cameroon over the course of this study. Phylogenetic analyses based on DNA sequence data of the internal transcribed spacer region and intervening 5.8S nrRNA gene, and partial fragments of the calmodulin, beta-tubulin, histone and the translation elongation factor 1-α genes, demonstrated that these isolates represent four new species, i.e. D.brideliae, D.cameroonensis, D.pseudoanacardii and D.rauvolfiae. Moreover, the description of D.isoberliniae is here emended, now incorporating the morphology of beta and gamma conidia produced by two of our endophytic isolates, which had never been documented in previous records. Moreover, the paraphyletic nature of the genus is discussed and suggestions are made for future revision of the genus.
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Affiliation(s)
- Christopher Lambert
- Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, GermanyDepartment of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/BraunschweigBraunschweigGermany
- Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Braunschweig, GermanyTechnische Universität BraunschweigBraunschweigGermany
- Molecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, GermanyMolecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI)BraunschweigGermany
| | - Lena Schweizer
- Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, GermanyDepartment of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/BraunschweigBraunschweigGermany
| | - Blondelle Matio Kemkuignou
- Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, GermanyDepartment of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/BraunschweigBraunschweigGermany
- Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Braunschweig, GermanyTechnische Universität BraunschweigBraunschweigGermany
| | - Elodie Gisèle M. Anoumedem
- Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, Yaoundé P.O. Box 47, CameroonUniversity of Yaoundé IYaoundeCameroon
| | - Simeon F. Kouam
- Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, Yaoundé P.O. Box 47, CameroonUniversity of Yaoundé IYaoundeCameroon
| | - Yasmina Marin-Felix
- Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, GermanyDepartment of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/BraunschweigBraunschweigGermany
- Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Braunschweig, GermanyTechnische Universität BraunschweigBraunschweigGermany
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Liu H, Park S, Sang H. Identification and Fungicide Control of Bipolaris sorokiniana Causing Leaf Spot and Blight on Common Hop ( Humulus lupulus) in Korea. Plant Dis 2023; 107:2939-2943. [PMID: 37189044 DOI: 10.1094/pdis-04-23-0752-sc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Hop (Humulus lupulus) is a perennial herbaceous vine belonging to the family Cannabaceae. This crop is commercially grown for the brewing industry for its bitter and aromatic flavor, as well as its antiseptic properties. In June 2021, leaf spot and blight was observed on common hop plants in Buan-gun, Jeollabuk-do, South Korea. The typical symptoms were small to large, dark-brown, necrotic lesions with yellow halos on the leaves. This study aimed to clarify the causal agent of this disease. Two fungal species, Alternaria alternata and Bipolaris sorokiniana, were isolated from the diseased leaf samples and identified by combining morphological observations and phylogenetic analysis using sequence datasets of internal transcribed spacer (ITS), Alt a1, rpb2, endoPG, and OPA10-2; and ITS, gpd, and tef1, respectively. Pathogenicity of the fungal isolates on detached leaves and living plants revealed that B. sorokiniana is the causal pathogen of this disease, while A. alternata is potentially a saprophyte. Fungicide sensitivity of the pathogen B. sorokiniana was further estimated in vitro using three classes of fungicides represented by fluxapyroxad, pyraclostrobin, and hexaconazole. The effective concentrations that inhibited 50% of spore germination (EC50) were 0.72, 1.90, and 0.68 μg ml-1, respectively. Moreover, all of these fungicides were able to control B. sorokiniana on detached common hop leaves at their recommended concentrations. In conclusion, this study reports leaf spot and blight of common hop caused by B. sorokiniana for the first time and proposes potential fungicides for this disease.
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Affiliation(s)
- Haifeng Liu
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Korea
| | - Sanghoon Park
- Hop&Hope, Agricultural Co. Ltd., Buan-gun 56319, Jeollabuk-do, Korea
| | - Hyunkyu Sang
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju 61186, Korea
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Sharma S, Strickland D, Hay F, Pethybridge SJ. First Report of Halo Blight on Hop Caused by Diaporthe humulicola in New York. Plant Dis 2022; 107:216. [PMID: 35640949 DOI: 10.1094/pdis-01-22-0202-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In late July and August 2015, foliar disease was observed in three hop (Humulus lupulus; unknown cultivars) yards in Ontario, Otsego, and Putnam counties, New York (NY). Disease incidence ranged between 70 and 90% of plants, and up to 25% of the leaves per plant were affected. Leaf symptoms were large, necrotic patches with a chlorotic halo (2 to 10 cm diam.). Leaves and dry, easily shattered cones were placed at high humidity for 10 days. Pycnidia were abundant in leaf lesions which extruded conidia. Pycnidia were also observed on cone bracts and bracteoles. Fifteen isolations were made from each yard by placing a pycnidium onto 2% water agar + 0.02% (w/v) ampicillin. Colonies were hyphal tipped and transferred to potato dextrose agar (PDA) before incubation at 20°C with a 12-h photoperiod. Colonies on PDA had flat mycelia and were white to cream in color. The isolation frequency was 100%. To induce sporulation, five isolates were grown on PDA with autoclaved alfalfa stems for 7 to 10 days. Alpha conidia were hyaline, and oval with obtuse ends. Mean alpha conidial dimensions were (n = 20): 9.1 m × 3.4 µm (BE1; Ontario Co.); 11.8 × 3.8 µm (BE34; Ontario Co.); 9.6 × 4.1 µm (BE10; Ontario Co.); 10.2 × 3.7 µm (BE52; Otsego Co.); and 10.3 × 3.6 µm (BE69; Putnam Co.). Beta conidia were not observed. DNA was extracted and PCR performed to amplify the internal transcribed spacer (ITS) region (primers ITS1/ITS4; White et al. 1990), translation elongation factor 1-α (TEF; EF1-728F/EF1-986R; Carbone and Kohn 1999), a partial region of β-tubulin (TUB; Bt2a/Bt2b; Glass and Donaldson 1995), a partial region of histone 3 (H3) (H3; CYLH3F/H3-1b Crous et al. 2004), and calmodulin (CAL; CAL-228F/CAL2Rd; Groenewald et al. 2013) genes. For all NY isolates, sequence similarity was >99% to D. humulicola CT2018-3 for the ITS region, and TEF, HIS, and CAL genes. Sequence similarity to CT2018-3 for the TUB region ranged from 86.96% (BE-1) to 96.15% (BE-10). . Analyses with the ITS, TEF, CAL, and HIS sequences supported our identification of the NY isolates as D. humulicola. Sequences were deposited in GenBank (OM370960 to OM370984). For pathogenicity testing, BE-34 and BE-69 were grown on PDA + autoclaved alfalfa stems at room temperature and a 12-h photoperiod for 10 days. Conidia were harvested by flooding the plate with sterile water. Conidial concentration was quantified, and the inoculum suspension diluted to ~5 105 (+ 0.01% polysorbate-20)/ml. Five cv. Cascade plants were sprayed with inoculum until run-off and covered with a plastic bag for 72 h. Non-inoculated control plants were sprayed with 0.01% polysorbate-20 and bagged. Plants were placed in a misting chamber and exposed to alternating 25°C light/18°C dark with a 16 h photoperiod. Mist was applied for 1 h daily. Necrotic lesions like the field specimens were observed on all inoculated plants after 28 days with no symptoms on control plants. Diseased leaves were detached and placed in a humid chamber for 2 days, and pycnidia observed in lesions. The reisolation frequency of D. humulicola was 100%. Conidia from the isolates had similar morphology to the original isolates. This is the first report of halo blight caused by D. humulicola on hop in NY. Halo blight has been reported on hop and associated with significant yield loss through cone shattering in MI (Higgins et al. 2021), CT (Allan-Perkins et al. 2020), and Quebec, Canada (Hatlen et al. 2021). Research is needed to determine if management is warranted.
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Affiliation(s)
- Sandeep Sharma
- Cornell University, 5922, Section of Plant Pathology and Plant Microbe Biology, 15 Castle Creek Dr, Barton Laboratory, Geneva, New York, United States, 14456;
| | - David Strickland
- Cornell University, Plant Pathology and Plant-Microbe Biology Section, 15 Castle Creek Drive, Barton Lab, Geneva, New York, United States, 14456;
| | - Frank Hay
- Cornell University, Plant Pathology and Plant-Microbe Biology Section, 630 West North Street, 120 Barton Laboratory, Geneva, New York, United States, 14456;
| | - Sarah Jane Pethybridge
- Cornell University, Plant Pathology and Plant-Microbe Biology, 630 West North Street, 211 Barton Laboratory, Geneva, New York, United States, 14456;
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Si YZ, Li DW, Zhong J, Huang L, Zhu LH. Diaporthe sapindicola sp. nov. Causes Leaf Spots of Sapindus mukorossi in China. Plant Dis 2022; 106:1105-1113. [PMID: 34752121 DOI: 10.1094/pdis-04-21-0777-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Sapindus mukorossi Gaertn. (Sapindaceae), or soapberry, is an important biodiesel tree in southern China. In recent years, leaf spot disease on soapberry has been observed frequently in a soapberry germplasm repository in Jianning County, Sanming City, Fujian province, China. The symptoms initially appeared as irregular, small, yellow spots, and the centers of the lesions became dark brown with time. Three fungal isolates from lesions were collected. Koch's postulates were performed, and their pathogenicity was confirmed. Morphologically, α-conidia from diseased tissues were single-celled, hyaline, smooth, clavate or ellipsoidal, and biguttulate, measuring 6.2 to 7.2 × 2.3 to 2.7 μm. In addition, the three isolates in this study developed three types (α, β, and γ) of conidia on potato dextrose agar, and their morphological characteristics matched those of Diaporthe. A phylogenetic analysis based on internal transcribed spacer, TEF, TUB, HIS, and CAL sequence data determined that the three isolates are a new species of Diaporthe. Based on both morphological and phylogenetic analyses, the causal fungus, Diaporthe sapindicola sp. nov., was described and illustrated.
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Affiliation(s)
- Yuan-Zhi Si
- College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - De-Wei Li
- The Connecticut Agricultural Experiment Station Valley Laboratory, Windsor, CT 06095, U.S.A
| | - Jing Zhong
- Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China
| | - Lin Huang
- College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Li-Hua Zhu
- College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
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Hatlen RJ, Higgins DS, Venne J, Rojas JA, Hausbeck M, Miles TD. First report of halo blight of hop (Humulus lupulus) caused by Diaporthe humulicola in Quebec, Canada. Plant Dis 2021; 106:1750. [PMID: 34798784 DOI: 10.1094/pdis-06-21-1332-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Halo blight of hop caused by Diaporthe humulicola has recently been reported in Michigan and Connecticut (Higgins et al. 2021, Allan-Perkins et al 2020). In August 2020 growers in Quebec, Canada reported necrotic foliar lesions and desiccation of the hop strobile (cone) on Chinook and Nugget cultivars. The foliar lesions were dry concentric circles with a chlorotic halo surrounding the lesions; no pycnidia were observed on leaves or cones. Up to 100% of the infected bract tissue was dry and easily shattered, the grower estimated that more than 90% of the plants in the hopyard exhibited symptoms. Twenty-six isolates were obtained from surface-sterilized leaf and cone tissue by plating the leading edge of lesions on potato dextrose agar. Fungal isolates were hyphal tipped and were incubated at 22°C with a 12 h photoperiod. After 21-days, all cultures were white to beige with pycnidia. DNA was extracted from cultures using the MagMAX Plant DNA Isolation Kit (Applied Biosystems, Foster City, CA). DNA amplification of a representative isolate (CD6C) was performed with primers ITS1/ITS4 (White et al. 1990) for the internal transcribed spacer (ITS), CYLH3F/H3-1b (Glass and Donaldson 1995) for histone 3 (HIS), and Ef1728f/EF1-986R (Carbone and Kohn 1999) for translation elongation factor 1-α (TEF). Amplification primers were used for bidirectional Sanger sequencing, reads were assembled using Geneious Prime (Biomatters, New Zealand), and identified using NCBI BLAST. BLAST results showed that the sequences for TEF, ITS, and HIS all had 100% pairwise identity to Diaporthe sp. 1-MI (MT909101, MT909099, MT909093, OK001342, MZ934713, OK001341). Futhermore, BLAST results showed that ITS and HIS have 100% pairwise identity D. humulicola (MN152929, MN180214). The TEF sequence also had 99.7% pairwise identity to D. humulicola (MN180209). Koch's postulates were conducted by inoculating six 3-mo-old 'Chinook' plants with conidia harvested from 28-day-old cultures and spraying 50 ml of inoculum (6 x 105 conidia/ml) or water to each plant. Plants were then stored in a greenhouse at 100% relative humidity at 22°C with a 14-h photo period. Lesions appeared on the adaxial side of the leaf after 21 days. D. humulicola was re-isolated from all infected leaf tissue, but not from any water inoculated plants and identified by conidial morphology using descriptions from Higgins et al. (2021). So far, Diaporthe sp. 1-MI appears to be synonymous with Diaporthe humulicola, but currently two names are being utilized (i.e. Diaporthe leaf spot and halo blight). In Higgins et al., (2021) it was proposed that the name halo blight might be more appropriate because disease symptoms are not confined to the leaves and cause significant blighting of cones. Halo blight caused by D. humulicola appears widespread in Michigan and Canada and may become an issue in other eastern North American growing regions with humid conditions.
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Affiliation(s)
- Ross Joaquin Hatlen
- Michigan State University College of Agriculture and Natural Resources, 115974, Department of Plant, Soil and Microbial Sciences, East Lansing, Michigan, United States;
| | - Douglas S Higgins
- Michigan State University, 3078, Plant Soil and Microbial Sciences , 612 Wilson Road, 164 PBL, East Lansing, Michigan, United States, 48824-1312;
| | - Julien Venne
- Ministère de l'Agriculture, des Pêcheries et de l'Alimentation, Gatineau, Quebec, Canada;
| | - J Alejandro Rojas
- University of Arkansas Fayetteville, 3341, Plant Pathology, 495 N. Campus Drive, PTSC 217, Fayetteville, Arkansas, United States, 72703;
| | - Mary Hausbeck
- Michigan State University, Plant Pathology, 140 Plant Biology Lab, East Lansing, Michigan, United States, 48824;
| | - Timothy D Miles
- Michigan State University, Department of Plant, Soil and Microbial Sciences, 105 CIPS, East Lansing, Michigan, United States, 48824;
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Ariyawansa HA, Tsai I, Wang JY, Withee P, Tanjira M, Lin SR, Suwannarach N, Kumla J, Elgorban AM, Cheewangkoon R. Molecular Phylogenetic Diversity and Biological Characterization of Diaporthe Species Associated with Leaf Spots of Camellia sinensis in Taiwan. Plants (Basel) 2021; 10:1434. [PMID: 34371637 PMCID: PMC8309328 DOI: 10.3390/plants10071434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/16/2022]
Abstract
Camellia sinensis is one of the major crops grown in Taiwan and has been widely cultivated around the island. Tea leaves are prone to various fungal infections, and leaf spot is considered one of the major diseases in Taiwan tea fields. As part of a survey on fungal species causing leaf spots on tea leaves in Taiwan, 19 fungal strains morphologically similar to the genus Diaporthe were collected. ITS (internal transcribed spacer), tef1-α (translation elongation factor 1-α), tub2 (beta-tubulin), and cal (calmodulin) gene regions were used to construct phylogenetic trees and determine the evolutionary relationships among the collected strains. In total, six Diaporthe species, including one new species, Diaporthe hsinchuensis, were identified as linked with leaf spot of C. sinensis in Taiwan based on both phenotypic characters and phylogeny. These species were further characterized in terms of their pathogenicity, temperature, and pH requirements under laboratory conditions. Diaporthe tulliensis, D. passiflorae, and D. perseae were isolated from C. sinensis for the first time. Furthermore, pathogenicity tests revealed that, with wound inoculation, only D. hongkongensis was pathogenic on tea leaves. This investigation delivers the first assessment of Diaporthe taxa related to leaf spots on tea in Taiwan.
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Affiliation(s)
- Hiran A. Ariyawansa
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan; (I.T.); (J.-Y.W.)
| | - Ichen Tsai
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan; (I.T.); (J.-Y.W.)
- Biodiversity and Climate Research Centre (BiK-F), 60325 Frankfurt am Main, Germany
- Department of Biological Science, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Jian-Yuan Wang
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei 10617, Taiwan; (I.T.); (J.-Y.W.)
| | - Patchareeya Withee
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (M.T.)
| | - Medsaii Tanjira
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (M.T.)
| | - Shiou-Ruei Lin
- Department of Tea Agronomy, Tea Research and Extension Station, Taoyuan 32654, Taiwan;
| | - Nakarin Suwannarach
- Research Centre of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; (N.S.); (J.K.)
- Innovative Agriculture Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jaturong Kumla
- Research Centre of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; (N.S.); (J.K.)
- Innovative Agriculture Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Abdallah M. Elgorban
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Ratchadawan Cheewangkoon
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (M.T.)
- Innovative Agriculture Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
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Higgins DS, Hatlen RJ, Byrne JM, Sakalidis ML, Miles TD, Hausbeck MK. Etiology of Halo Blight in Michigan Hopyards. Plant Dis 2021; 105:859-872. [PMID: 32840437 DOI: 10.1094/pdis-05-20-0924-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Michigan's hop acreage ranks fourth nationally, but the state's growers contend with unique disease challenges resulting from frequent rainfall and high humidity. In August 2018, a Michigan hop grower reported necrosis and blighting of foliage and shattering of cones resulting in yield loss. Irregular-shaped lesions developed on leaves, surrounded by a halo of chlorotic tissue, and cone bracts became brown. Pycnidia were observed in symptomatic tissue. The goal of this study was to identify and characterize the causal agent of symptoms in leaf and cone tissue. In symptomatic leaves, 15 of 19 isolates recovered had 96.4% internal transcribed spacer rDNA (ITSrDNA) homology with Diaporthe nomurai. Bayesian and maximum likelihood analyses were performed on a subset of isolates using ITSrDNA, histone H3, beta-tubulin, and elongation factor 1 alpha. Bootstrap and posterior probabilities supported a unique cluster of Diaporthe sp. 1-MI isolates most closely related to the Diaporthe arecae species complex, Diaporthe hongkongensis, and Diaporthe multigutullata. Diaporthe sp. 1-MI was pathogenic in detached leaf and whole plant assays. Single-spore isolates from pycnidia originating from cones and leaves shared 100% ITSrDNA homology with Diaporthe sp. 1-MI obtained from the lesion margins of leaves collected in 2018. The distribution of Diaporthe sp. 1-MI was widespread among 347 cones collected from 15 Michigan hop yards and accounted for >38% of fungi recovered from cones in three hop yards. Diaporthe sp. 1-MI causing halo and cone blight presents a new disease management challenge for Michigan hop growers.
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Affiliation(s)
- Douglas S Higgins
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Ross J Hatlen
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Jan M Byrne
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Monique L Sakalidis
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
- Department of Forestry, Michigan State University, East Lansing, MI 48824
| | - Timothy D Miles
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Mary K Hausbeck
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
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