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Chen C, Keunecke H, Bemm F, Gyetvai G, Neu E, Kopisch‐Obuch FJ, McDonald BA, Stapley J. GWAS reveals a rapidly evolving candidate avirulence effector in the Cercospora leaf spot pathogen. MOLECULAR PLANT PATHOLOGY 2024; 25:e13407. [PMID: 38009399 PMCID: PMC10799204 DOI: 10.1111/mpp.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/09/2023] [Accepted: 11/09/2023] [Indexed: 11/28/2023]
Abstract
The major resistance gene BvCR4 recently bred into sugar beet hybrids provides a high level of resistance to Cercospora leaf spot caused by the fungal pathogen Cercospora beticola. The occurrence of pathogen strains that overcome BvCR4 was studied using field trials in Switzerland conducted under natural disease pressure. Virulence of a subset of these strains was evaluated in a field trial conducted under elevated artificial disease pressure. We created a new C. beticola reference genome and mapped whole genome sequences of 256 isolates collected in Switzerland and Germany. These were combined with virulence phenotypes to conduct three separate genome-wide association studies (GWAS) to identify candidate avirulence genes. We identified a locus associated with avirulence containing a putative avirulence effector gene named AvrCR4. All virulent isolates either lacked AvrCR4 or had nonsynonymous mutations within the gene. AvrCR4 was present in all 74 isolates from non-BvCR4 hybrids, whereas 33 of 89 isolates from BvCR4 hybrids carried a deletion. We also mapped genomic data from 190 publicly available US isolates to our new reference genome. The AvrCR4 deletion was found in only one of 95 unique isolates from non-BvCR4 hybrids in the United States. AvrCR4 presents a unique example of an avirulence effector in which virulent alleles have only recently emerged. Most likely these were selected out of standing genetic variation after deployment of BvCR4. Identification of AvrCR4 will enable real-time screening of C. beticola populations for the emergence and spread of virulent isolates.
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Affiliation(s)
- Chen Chen
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | | | | | | | - Enzo Neu
- KWS SAAT SE & Co. KGaAEinbeckGermany
| | | | - Bruce A. McDonald
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | - Jessica Stapley
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
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2
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Hernandez AP, Bublitz DM, Wenzel TJ, Ruth SK, Bloomingdale C, Mettler DC, Bloomquist MW, Hanson LE, Willbur JF. An in-field heat treatment to reduce Cercospora beticola survival in plant residue and improve Cercospora leaf spot management in sugarbeet. FRONTIERS IN PLANT SCIENCE 2023; 14:1100595. [PMID: 37229110 PMCID: PMC10204640 DOI: 10.3389/fpls.2023.1100595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 03/30/2023] [Indexed: 05/27/2023]
Abstract
Introduction Sugarbeets account for 55 to 60% of U.S. sugar production. Cercospora leaf spot (CLS), primarily caused by the fungal pathogen Cercospora beticola, is a major foliar disease of sugarbeet. Since leaf tissue is a primary site of pathogen survival between growing seasons, this study evaluated management strategies to reduce this source of inoculum. Methods Fall- and spring-applied treatments were evaluated over three years at two study sites. Treatments included standard plowing or tilling immediately post-harvest, as well as the following alternatives to tillage: a propane-fueled heat treatment either in the fall immediately pre-harvest or in the spring prior to planting, and a desiccant (saflufenacil) application seven days pre-harvest. After fall treatments, leaf samples were evaluated to determine C. beticola viability. The following season, inoculum pressure was measured by monitoring CLS severity in a susceptible beet variety planted into the same plots and by counting lesions on highly susceptible sentinel beets placed into the field at weekly intervals (fall treatments only). Results No significant reductions in C. beticola survival or CLS were observed following fall-applied desiccant. The fall heat treatment, however, significantly reduced lesion sporulation (2019-20 and 2020-21, P < 0.0001; 2021-22, P < 0.05) and C. beticola isolation (2019-20, P < 0.05) in at-harvest samples. Fall heat treatments also significantly reduced detectable sporulation for up to 70- (2021-22, P < 0.01) or 90-days post-harvest (2020-21, P < 0.05). Reduced numbers of CLS lesions were observed on sentinel beets in heat-treated plots from May 26-June 2 (P < 0.05) and June 2-9 (P < 0.01) in 2019, as well as June 15-22 (P < 0.01) in 2020. Both fall- and spring-applied heat treatments also reduced the area under the disease progress curve for CLS assessed the season after treatments were applied (Michigan 2020 and 2021, P < 0.05; Minnesota 2019, P < 0.05; 2021, P < 0.0001). Discussion Overall, heat treatments resulted in CLS reductions at levels comparable to standard tillage, with more consistent reductions across year and location. Based on these results, heat treatment of fresh or overwintered leaf tissue could be used as an integrated tillage-alternative practice to aid in CLS management.
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Affiliation(s)
- Alexandra P. Hernandez
- Department of Plant, Soil and Microbial Sciences, Potato and Sugarbeet Pathology, Michigan State University, East Lansing, MI, United States
| | - Daniel M. Bublitz
- Department of Plant, Soil and Microbial Sciences, Michigan State University Extension and Sugarbeet Advancement, Frankenmuth, MI, United States
| | - Thomas J. Wenzel
- Department of Plant, Soil and Microbial Sciences, Michigan State University Extension and Sugarbeet Advancement, Frankenmuth, MI, United States
| | - Sarah K. Ruth
- Department of Plant, Soil and Microbial Sciences, Potato and Sugarbeet Pathology, Michigan State University, East Lansing, MI, United States
| | - Chris Bloomingdale
- Department of Plant, Soil and Microbial Sciences, Potato and Sugarbeet Pathology, Michigan State University, East Lansing, MI, United States
| | - David C. Mettler
- Southern Minnesota Beet Sugar Cooperative, Renville, MN, United States
| | | | - Linda E. Hanson
- Sugarbeet and Bean Research Unit, United States Department of Agriculture – Agricultural Research Services, East Lansing, MI, United States
| | - Jaime F. Willbur
- Department of Plant, Soil and Microbial Sciences, Potato and Sugarbeet Pathology, Michigan State University, East Lansing, MI, United States
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Marin MV, Wang NY, Seijo T, Druffel KL, McGuin RL, Deng Z, Peres NA. Pseudocercospora pancratii Causing Leaf Spots on Commercial Blackberry ( Rubus sp.) in Florida. PLANT DISEASE 2023; 107:131-135. [PMID: 35749667 DOI: 10.1094/pdis-04-22-0900-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: 06/15/2023]
Abstract
Blackberry (Rubus L. subgenus Rubus Watson) is a deciduous berry crop that is the fourth most economically important berry crop, and its production is expanding in the southeastern United States. However, since most commercially available cultivars were bred under temperate conditions, they are not always well adapted and could be threatened by new pathogen populations inhabiting subtropical areas. In 2017, plants showing purple or brown leaf spots and angular-to-irregular lesions on both leaf surfaces, with clusters of black conidiophores at the center, were observed in a field trial at the University of Florida's Gulf Coast Research and Education Center (UF/GCREC) in Wimauma, FL. A fungus resembling Cercospora/Pseudocercospora was isolated from the lesions. The ribosomal DNA internal transcribed spacers, the translation elongation factor 1-alpha, and the actin genes were amplified and sequenced. Based on the phylogenetic analysis, the closest related species was Pseudocercospora pancratii. Pathogenicity assays and subsequent reisolation confirmed that this species is the causal agent of the disease. Among eight cultivars screened, no complete resistance was found. However, 'Osage' was the least susceptible, and 'Kiowa' was the most susceptible. This study is the first report of P. pancratii causing leaf spots on blackberry worldwide, and it may help shape future research into disease epidemiology and management for a crop that is rapidly expanding but has very limited disease information currently available for Florida growers.
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Affiliation(s)
- Marcus V Marin
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Nan-Yi Wang
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Teresa Seijo
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Keri L Druffel
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Rebeca L McGuin
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Zhanao Deng
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
| | - Natalia A Peres
- University of Florida, Plant Pathology Department, Gulf Coast Research and Education Center, Wimauma, FL 33598
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Zhang X, Lv H, Tian M, Dong Z, Fu Q, Sun J, Huang Q, Wang J. Colonization characteristics of fungi in Polygonum hydropipe L. and Polygonum lapathifolium L. and its effect on the content of active ingredients. FRONTIERS IN PLANT SCIENCE 2022; 13:984483. [PMID: 36247635 PMCID: PMC9554492 DOI: 10.3389/fpls.2022.984483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 08/18/2022] [Indexed: 06/16/2023]
Abstract
Polygonum hydropiper, is a plant of the Persicaria genus, which is commonly used to treat various diseases, including gastrointestinal disorders, neurological disorders, inflammation, and diarrhea. However, because of different local standards of P. hydropiper, people often confuse it with Polygonum lapathifolium L. and other closely related plants. This poses a serious threat to the safety and efficacy of the clinical use of P. hydropiper. This study aims to determine the six active ingredients of P. hydropiper and P. lapathifolium. Then the endophytic fungi and rhizosphere soil of the two species were sequenced by Illumina Miseq PE300. The results show significant differences between the community composition of the leaves, stems, and roots of the P. hydropiper and the P. lapathifolium in the same soil environment. Of the six secondary metabolites detected, five had significant differences between P. hydropiper and P. lapathifolium. Then, we evaluated the composition of the significantly different communities between P. hydropiper and P. lapathifolium. In the P. hydropiper, the relative abundance of differential communities in the leaves was highest, of which Cercospora dominated the differential communities in the leaves and stem; in the P. lapathifolium, the relative abundance of differential community in the stem was highest, and Cladosporium dominated the differential communities in the three compartments. By constructing the interaction network of P. hydropiper and P. lapathifolium and analyzing the network nodes, we found that the core community in P. hydropiper accounted for 87.59% of the total community, dominated by Cercospora; the core community of P. lapathifolium accounted for 19.81% of the total community, dominated by Sarocladium. Of these core communities, 23 were significantly associated with active ingredient content. Therefore, we believe that the community from Cercospora significantly interferes with recruiting fungal communities in P. hydropiper and affects the accumulation of secondary metabolites in the host plant. These results provide an essential foundation for the large-scale production of P. hydropiper. They indicate that by colonizing specific fungal communities, secondary metabolic characteristics of host plants can be helped to be shaped, which is an essential means for developing new medicinal plants.
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Affiliation(s)
- Xiaorui Zhang
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Hongyang Lv
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Maoying Tian
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Zhaowei Dong
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Qinwen Fu
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jilin Sun
- Sichuan Fuzheng Pharmaceutical Co., Ltd., Chengdu, China
| | - Qinwan Huang
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jin Wang
- State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, China
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Spanner R, Neubauer J, Heick TM, Grusak MA, Hamilton O, Rivera-Varas V, de Jonge R, Pethybridge S, Webb KM, Leubner-Metzger G, Secor GA, Bolton MD. Seedborne Cercospora beticola Can Initiate Cercospora Leaf Spot from Sugar Beet ( Beta vulgaris) Fruit Tissue. PHYTOPATHOLOGY 2022; 112:1016-1028. [PMID: 34844416 DOI: 10.1094/phyto-03-21-0113-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Cercospora leaf spot (CLS) is a globally important disease of sugar beet (Beta vulgaris) caused by the fungus Cercospora beticola. Long-distance movement of C. beticola has been indirectly evidenced in recent population genetic studies, suggesting potential dispersal via seed. Commercial sugar beet "seed" consists of the reproductive fruit (true seed surrounded by maternal pericarp tissue) coated in artificial pellet material. In this study, we confirmed the presence of viable C. beticola in sugar beet fruit for 10 of 37 tested seed lots. All isolates harbored the G143A mutation associated with quinone outside inhibitor resistance, and 32 of 38 isolates had reduced demethylation inhibitor sensitivity (EC50 > 1 µg/ml). Planting of commercial sugar beet seed demonstrated the ability of seedborne inoculum to initiate CLS in sugar beet. C. beticola DNA was detected in DNA isolated from xylem sap, suggesting the vascular system is used to systemically colonize the host. We established nuclear ribosomal internal transcribed spacer region amplicon sequencing using the MinION platform to detect fungi in sugar beet fruit. Fungal sequences from 19 different genera were identified from 11 different sugar beet seed lots, but Fusarium, Alternaria, and Cercospora were consistently the three most dominant taxa, comprising an average of 93% relative read abundance over 11 seed lots. We also present evidence that C. beticola resides in the pericarp of sugar beet fruit rather than the true seed. The presence of seedborne inoculum should be considered when implementing integrated disease management strategies for CLS of sugar beet in the future.
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Affiliation(s)
- Rebecca Spanner
- Edward T. Schafer Agricultural Research Center, United States Department of Agriculture-Agricultural Research Service, Fargo, ND, U.S.A
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
| | - Jonathan Neubauer
- Edward T. Schafer Agricultural Research Center, United States Department of Agriculture-Agricultural Research Service, Fargo, ND, U.S.A
| | - Thies M Heick
- Institute for Agroecology, Aarhus University, Slagelse, Denmark
| | - Michael A Grusak
- Edward T. Schafer Agricultural Research Center, United States Department of Agriculture-Agricultural Research Service, Fargo, ND, U.S.A
| | - Olivia Hamilton
- Edward T. Schafer Agricultural Research Center, United States Department of Agriculture-Agricultural Research Service, Fargo, ND, U.S.A
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
| | | | - Ronnie de Jonge
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Sarah Pethybridge
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY, U.S.A
| | - Kimberley M Webb
- Soil Management and Sugar Beet Research Unit, United States Department of Agriculture-Agricultural Research Service, Fort Collins, CO, U.S.A
| | | | - Gary A Secor
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
| | - Melvin D Bolton
- Edward T. Schafer Agricultural Research Center, United States Department of Agriculture-Agricultural Research Service, Fargo, ND, U.S.A
- Department of Plant Pathology, North Dakota State University, Fargo, ND, U.S.A
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Heck DW, Kikkert JR, Hanson LE, Pethybridge SJ. Development of a Sequential Sampling Plan using Spatial Attributes of Cercospora Leaf Spot Epidemics of Table Beet in New York. PLANT DISEASE 2021; 105:2453-2465. [PMID: 33529070 DOI: 10.1094/pdis-07-20-1619-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Sampling strategies that effectively assess disease intensity in the field are important to underpin management decisions. To develop a sequential sampling plan for the incidence of Cercospora leaf spot (CLS), caused by Cercospora beticola, 31 table beet fields were assessed in the state of New York. Assessments of CLS incidence were performed in six leaves arbitrarily selected in 51 sampling locations along each of three to six linear transects per field. Spatial pattern analyses were performed, and results were used to develop sequential sampling estimation and classification models. CLS incidence (p) ranged from 0.13 to 0.92 with a median of 0.31, and beta-binomial distribution, which is reflective of aggregation, best described the spatial patterns observed. Aggregation was commonly detected (>95%) by methods using the point-process approach, runs analyses, and autocorrelation up to the fourth spatial lag. For Spatial Analysis by Distance Indices, or SADIE, 45% of the datasets were classified as a random pattern. In the sequential sampling estimation and classification models, disease units are sampled until a prespecified target is achieved. For estimation, the goal was sampling CLS incidence with a preselected coefficient of variation (C). Achieving the C = 0.1 was challenging with <51 sampling units, and only observed on datasets with incidence >0.3. Reducing the level of precision, i.e., increasing C to 0.2, allowed the preselected C to be achieved with a lower number of sampling units and with an estimated incidence ([Formula: see text]) close to the true value of p. For classification, the goal was to classify the datasets above or below prespecified thresholds (pt) used for CLS management. The average sample number, or ASN, was determined by Monte Carlo simulations, and was between 20 and 45 at disease incidence values close to pt, and approximately 11 when far from pt. Correct decisions occurred in >76% of the validation datasets. Results indicated these sequential sampling plans can be used to effectively assess CLS incidence in table beet fields.
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Affiliation(s)
- Daniel W Heck
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Julie R Kikkert
- Cornell Vegetable Program, Cornell Cooperative Extension, Canandaigua, NY 14424
| | - Linda E Hanson
- United States Department of Agriculture - Agricultural Research Service and Department of Plant Soil and Microbial Science, Michigan State University, East Lansing, MI 48824
| | - Sarah J Pethybridge
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Addison CK, Angira B, Cerioli T, Groth DE, Richards JK, Linscombe SD, Famoso AN. Identification and mapping of a novel resistance gene to the rice pathogen, Cercospora janseana. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2021; 134:2221-2234. [PMID: 33825949 DOI: 10.1007/s00122-021-03821-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
The genetic architecture of resistance to Cercospora janseana was examined, and a single resistance locus was identified. A SNP marker was identified and validated for utilization in U.S. breeding germplasm Cercospora janseana (Racib.) is a fungal pathogen that causes narrow brown leaf spot (NBLS) in rice. Although NBLS is a major disease in the southern United States and variation in resistance among U.S. rice germplasm exists, little is known about the genetic architecture underlying the trait. In this study, a recombinant inbred line population was evaluated for NBLS resistance under natural disease infestation in the field across three years. A single, large-effect QTL, CRSP-2.1, was identified that explained 81.4% of the phenotypic variation. The QTL was defined to a 532 kb physical interval and 13 single nucleotide polymorphisms (SNPs) were identified across the region to characterize the haplotype diversity present in U.S. rice germplasm. A panel of 387 U.S. rice germplasm was genotyped with the 13 haplotype SNPs and phenotyped over two years for NBLS resistance. Fourteen haplotypes were identified, with six haplotypes accounting for 94% of the panel. The susceptible haplotype from the RIL population was the only susceptible haplotype observed in the U.S. germplasm. A single SNP was identified that distinguished the susceptible haplotype from all resistant haplotypes, explaining 52.7% of the phenotypic variation for NBLS resistance. Pedigree analysis and haplotype characterization of historical germplasm demonstrated that the susceptible haplotype was introduced into Southern U.S. germplasm through the California line L-202 into the Louisiana variety Cypress. Cypress was extensively used as a parent over the last 25 years, resulting in the susceptible CRSP-2.1 allele increasing in frequency from zero to 44% in the modern U.S. germplasm panel.
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Affiliation(s)
- Christopher K Addison
- School of Plant, Environmental and Soil Science, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Brijesh Angira
- H. Rouse Caffey Rice Research Station, Louisiana State University Agricultural Center, 1373 Caffey Rd, Rayne, LA, 70578, USA
| | - Tommaso Cerioli
- School of Plant, Environmental and Soil Science, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Donald E Groth
- H. Rouse Caffey Rice Research Station, Louisiana State University Agricultural Center, 1373 Caffey Rd, Rayne, LA, 70578, USA
| | - Jonathan K Richards
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
| | - Steven D Linscombe
- H. Rouse Caffey Rice Research Station, Louisiana State University Agricultural Center, 1373 Caffey Rd, Rayne, LA, 70578, USA
| | - Adam N Famoso
- H. Rouse Caffey Rice Research Station, Louisiana State University Agricultural Center, 1373 Caffey Rd, Rayne, LA, 70578, USA.
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Rangel LI, Spanner RE, Ebert MK, Pethybridge SJ, Stukenbrock EH, de Jonge R, Secor GA, Bolton MD. Cercospora beticola: The intoxicating lifestyle of the leaf spot pathogen of sugar beet. MOLECULAR PLANT PATHOLOGY 2020; 21:1020-1041. [PMID: 32681599 PMCID: PMC7368123 DOI: 10.1111/mpp.12962] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/15/2020] [Accepted: 05/17/2020] [Indexed: 05/07/2023]
Abstract
Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. TAXONOMY Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora. HOST RANGE Well-known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad-leaved dock) families. DISEASE SYMPTOMS Leaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. MANAGEMENT Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. USEFUL WEBSITE: https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037.
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Affiliation(s)
- Lorena I. Rangel
- Northern Crop Science LaboratoryU.S. Department of Agriculture ‐ Agricultural Research ServiceFargoNDUSA
| | - Rebecca E. Spanner
- Northern Crop Science LaboratoryU.S. Department of Agriculture ‐ Agricultural Research ServiceFargoNDUSA
- Department of Plant PathologyNorth Dakota State UniversityFargoNDUSA
| | - Malaika K. Ebert
- Northern Crop Science LaboratoryU.S. Department of Agriculture ‐ Agricultural Research ServiceFargoNDUSA
- Department of Plant PathologyNorth Dakota State UniversityFargoNDUSA
- Present address:
Department of Plant BiologyMichigan State UniversityEast LansingMIUSA
| | - Sarah J. Pethybridge
- Plant Pathology & Plant‐Microbe Biology SectionSchool of Integrative Plant ScienceCornell AgriTech at The New York State Agricultural Experiment StationCornell UniversityGenevaNYUSA
| | - Eva H. Stukenbrock
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Christian‐Albrechts University of KielKielGermany
| | - Ronnie de Jonge
- Department of Plant‐Microbe InteractionsUtrecht UniversityUtrechtNetherlands
| | - Gary A. Secor
- Department of Plant PathologyNorth Dakota State UniversityFargoNDUSA
| | - Melvin D. Bolton
- Northern Crop Science LaboratoryU.S. Department of Agriculture ‐ Agricultural Research ServiceFargoNDUSA
- Department of Plant PathologyNorth Dakota State UniversityFargoNDUSA
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Pethybridge SJ, Sharma S, Hansen Z, Kikkert JR, Olmstead DL, Hanson LE. Optimizing Cercospora Leaf Spot Control in Table Beet Using Action Thresholds and Disease Forecasting. PLANT DISEASE 2020; 104:1831-1840. [PMID: 32357122 DOI: 10.1094/pdis-02-20-0246-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, is the dominant foliar disease affecting table-beet production in New York. CLS epidemics occur annually and, if uncontrolled, will rapidly lead to defoliation. In broad-acre production, season-long maintenance of healthy leaves is important to facilitate harvest by top-pulling. Fungicides are the dominant means of CLS control and applications are initiated at an action threshold of 1 CLS lesion/leaf. Regular fungicide application occurs thereafter without regard for scheduling based on weather-based risk. The current action threshold was evaluated with selected fungicides in two replicated field trials. Copper oxychloride + copper hydroxide and propiconazole significantly improved CLS control if initiated prior to infection. Pydiflumetofen + difenoconazole significantly reduced area under the disease progress stairs compared with other fungicides tested and was most efficacious when applications began at 1 CLS lesion/leaf. Six replicated field trials also evaluated the utility of scheduling fungicides on weather-based risk rather than a calendar approach. Two risk thresholds (moderate and high) integrating the accumulation of daily infection values based on temperature and relative humidity from a forecaster for CLS in sugar beet were evaluated. Applications of pydiflumetofen + difenoconazole were reduced from three to two by using the forecaster at either risk threshold compared with calendar applications without affecting CLS control. For propiconazole, the moderate risk threshold provided CLS control equivalent to calendar applications and saved one spray per season. Thus, there was substantial scope to reduce spray frequency by scheduling based on weather-based risk rather than calendar applications. The optimal risk thresholds for pydiflumetofen + difenoconazole and propiconazole were high and moderate, respectively. In these trials, periods of high risk occurred less frequently than moderate risk, increasing the reapplication intervals and, hence, represented a less conservative approach to disease management.
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Affiliation(s)
- Sarah J Pethybridge
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456, U.S.A
| | - Sandeep Sharma
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456, U.S.A
| | - Zachariah Hansen
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - Julie R Kikkert
- Cornell Vegetable Program, Cornell Cooperative Extension, Canandaigua, NY 14424, U.S.A
| | - Daniel L Olmstead
- New York State Integrated Pest Management Program, Cornell AgriTech, Cornell University, Geneva, NY 14456, U.S.A
| | - Linda E Hanson
- United States Department of Agriculture-Agricultural Research Service and Department of Plant Soil and Microbial Science, Michigan State University, East Lansing, MI 48824, U.S.A
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10
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Knight NL, Koenick LB, Sharma S, Pethybridge SJ. Detection of Cercospora beticola and Phoma betae on Table Beet Seed using Quantitative PCR. PHYTOPATHOLOGY 2020; 110:943-951. [PMID: 31939719 DOI: 10.1094/phyto-11-19-0412-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cercospora beticola and Phoma betae are important pathogens of table beet, sugar beet, and Swiss chard (Beta vulgaris subsp. vulgaris), causing Cercospora leaf spot (CLS) and Phoma leaf spot, root rot, and damping-off, respectively. Both pathogens may be seedborne; however, limited evidence is available for seed infestation by C. beticola. Due to the limitations of culture-based seed assessment methods, detection of these pathogens was investigated using PCR. A P. betae-specific quantitative PCR assay was developed and used in conjunction with a C. beticola-specific assay to assess the presence of pathogen DNA in 12 table beet seed lots. DNA of C. beticola and P. betae was detected in four and eight seed lots, respectively. Plate tests and BIO-PCR confirmed the viability of each pathogen; however, competitive growth of other microbes and low incidence limited the frequency and sensitivity of detection in some seed lots. The results for P. betae support previously described infestation of seed. Further investigation of C. beticola-infested seed lots indicated the ability of seedborne C. beticola to cause CLS on plants grown from infested seed. Detection of viable C. beticola on table beet seed demonstrates the potential for pathogen dispersal and disease initiation via infested seed, and provides valuable insight into the epidemiology of CLS. Surveys of commercial table beet seed are required to determine the frequency and source of C. beticola seed infestation and its role as primary inoculum for epidemics, and to evaluate the effectiveness of seed treatments.
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Affiliation(s)
- Noel L Knight
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
| | - Lori B Koenick
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
| | - Sandeep Sharma
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
| | - Sarah J Pethybridge
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
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11
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Knight NL, Vaghefi N, Kikkert JR, Pethybridge SJ. Alternative Hosts of Cercospora beticola in Field Surveys and Inoculation Trials. PLANT DISEASE 2019; 103:1983-1990. [PMID: 31242133 DOI: 10.1094/pdis-01-19-0229-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cercospora beticola, the cause of Cercospora leaf spot (CLS) of sugar beet and table beet, has a broad range of potential alternative hosts. The role of these hosts as inoculum sources in the field is unclear and has had limited investigation since the advent of DNA-based pathogen identification. The presence of C. beticola on alternative hosts associated with table beet fields of New York was assessed in field surveys during 2016. Lesions were collected, and 71 cercosporoid conidia were isolated for phylogenetic comparison. C. beticola was identified from Solanum ptycanthum (n = 4), Chenopodium album (n = 2), and Spinacia oleracea (n = 1), whereas C. chenopodii was identified on Chenopodium album (n = 51). Artificial inoculation of 21 plants species demonstrated that C. beticola was pathogenic to Brassica kaber, Chenopodium album, Carthamus tinctorius, Rumex obtusifolius, and Spinacia oleracea. These results indicate that although C. beticola may be pathogenic to a range of plant species, the role of symptomatic tissue for inoculum production on alternative hosts in the field appears limited. Observations of C. beticola on necrotic and naturally senescent tissue suggest saprophytic survival on plant debris of a range of species, which has implications for CLS epidemics and disease management.
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Affiliation(s)
- Noel L Knight
- 1Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Niloofar Vaghefi
- 1Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Julie R Kikkert
- 2Cornell Vegetable Program, Cornell Cooperative Extension, Canandaigua, NY 14424
| | - Sarah J Pethybridge
- 1Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
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Knight NL, Vaghefi N, Kikkert JR, Bolton MD, Secor GA, Rivera VV, Hanson LE, Nelson SC, Pethybridge SJ. Genetic Diversity and Structure in Regional Cercospora beticola Populations from Beta vulgaris subsp. vulgaris Suggest Two Clusters of Separate Origin. PHYTOPATHOLOGY 2019; 109:1280-1292. [PMID: 30785376 DOI: 10.1094/phyto-07-18-0264-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cercospora leaf spot, caused by Cercospora beticola, is a highly destructive disease of Beta vulgaris subsp. vulgaris worldwide. C. beticola populations are usually characterized by high genetic diversity, but little is known of the relationships among populations from different production regions around the world. This information would be informative of population origin and potential pathways for pathogen movement. For the current study, the genetic diversity, differentiation, and relationships among 948 C. beticola isolates in 28 populations across eight geographic regions were investigated using 12 microsatellite markers. Genotypic diversity, as measured by Simpson's complement index, ranged from 0.18 to 1.00, while pairwise index of differentiation values ranged from 0.02 to 0.42, with the greatest differentiation detected between two New York populations. In these populations, evidence for recent expansion was detected. Assessment of population structure identified two major clusters: the first associated with New York, and the second with Canada, Chile, Eurasia, Hawaii, Michigan, North Dakota, and one population from New York. Inferences of gene flow among these regions suggested that the source for one cluster likely is Eurasia, whereas the source for the other cluster is not known. These results suggest a shared origin of C. beticola populations across regions, except for part of New York, where population divergence has occurred. These findings support the hypothesis that dispersal of C. beticola occurs over long distances.
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Affiliation(s)
- Noel L Knight
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Niloofar Vaghefi
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Julie R Kikkert
- 2 Cornell Vegetable Program, Cornell Cooperative Extension, Canandaigua, NY 14424
| | - Melvin D Bolton
- 3 U.S. Department of Agriculture Agricultural Research Service (USDA ARS), Red River Valley Agricultural Research Center, Fargo, ND 58102
| | - Gary A Secor
- 4 Department of Plant Pathology, North Dakota State University, Fargo, ND 58105
| | - Viviana V Rivera
- 4 Department of Plant Pathology, North Dakota State University, Fargo, ND 58105
| | - Linda E Hanson
- 5 USDA ARS Sugar Beet and Bean Research Unit, Michigan State University, East Lansing, MI 48824; and
| | - Scot C Nelson
- 6 Department of Tropical Plant and Soil Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, HI 96822
| | - Sarah J Pethybridge
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
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13
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Knight NL, Vaghefi N, Hansen ZR, Kikkert JR, Pethybridge SJ. Temporal Genetic Differentiation of Cercospora beticola Populations in New York Table Beet Fields. PLANT DISEASE 2018; 102:2074-2082. [PMID: 30156961 DOI: 10.1094/pdis-01-18-0175-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Annual epidemics of Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, can result in substantial defoliation in table beet fields in New York. High allelic and genotypic diversity have been described within C. beticola populations; however, information on the temporal stability of populations is lacking. C. beticola isolates were obtained from symptomatic leaves in three table beet fields in successive years. Two of the fields were organic mixed-cropping farms and the third was managed conventionally in a broad-acre cropping system. C. beticola isolates (n = 304) were genotyped using 12 microsatellite markers. Genotypic diversity (Simpson's complement index = 0.178 to 0.990), allele frequencies, and indices of differentiation between years varied. Pairwise index of differentiation values ranged from 0.02 to 0.25 for clone-corrected data, and indicated significant genetic differentiation at Farm 2. No multilocus genotype was shared between years. The shift in multilocus genotypes between years questions the role of clonally reproducing primary inoculum. Collectively, these results suggest that a dominant inoculum source for initiating annual CLS epidemics is external to the field of interest. These findings have implications for CLS disease management in conventional and organic table beet production.
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Affiliation(s)
- Noel L Knight
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Niloofar Vaghefi
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Zachariah R Hansen
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | | | - Sarah J Pethybridge
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
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Challenges and Prospects for Building Resilient Disease Management Strategies and Tactics for the New York Table Beet Industry. AGRONOMY-BASEL 2018. [DOI: 10.3390/agronomy8070112] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Vogel J, Kenter C, Holst C, Märländer B. New Generation of Resistant Sugar Beet Varieties for Advanced Integrated Management of Cercospora Leaf Spot in Central Europe. FRONTIERS IN PLANT SCIENCE 2018; 9:222. [PMID: 29535743 PMCID: PMC5835311 DOI: 10.3389/fpls.2018.00222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/05/2018] [Indexed: 05/23/2023]
Abstract
Cercospora leaf spot (CLS) epidemics in sugar beet have been increasing in recent years causing higher use of fungicides. Concomitantly, the availability of effective fungicides is at risk because of resistance development in the fungus, the lack of new active ingredients as well as restrictive approval practices. A key option for an integrated management of CLS is cultivation of resistant varieties. Because of the yield penalty in resistant varieties, acceptance in commercial practice so far has been low. The aim of our study was to characterize recent sugar beet varieties registered in Germany in terms of resistance and tolerance to CLS and their value for integrated pest management. The genetic basis of CLS resistance in varieties is protected by intellectual property rights even after variety registration and not open to the public due to economic competition. To gain reliable data for cultivation, varieties have to be tested for their resistance traits under field conditions at varying levels of infection with Cercospora beticola. In collaboration with variety related stakeholders, 15 sugar beet varieties were tested in 49 field trials in Germany from 2014 to 2016 for their yield response to CLS. The trials were set up in a split-plot design with and without infection (i.e., with and without fungicide). The classification of varietal reaction to CLS is based on symptomatic leaf area (susceptibility) and the resulting relative yield loss (tolerance). Since the relation between both parameters varied among varieties, it was used as an additional parameter to describe tolerance. On this basis, three groups of varieties were identified. They can be characterized as a susceptible, a resistant and a presumably tolerant cluster. A comparison of the data with an older dataset originating from 2009 to 2011 revealed that yield performance of recent varieties with resistance to C. beticola caught up with susceptible varieties due to breeding progress. They showed no yield penalty in the absence of the disease and better economic performance than susceptible varieties. It is assumed that these varieties will allow a substantial reduction of fungicide use for an advanced integrated pest management under central European conditions.
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Affiliation(s)
- Johannes Vogel
- Institute of Sugar Beet Research at the University of Göttingen, Göttingen, Germany
- Department of Agricultural Economics and Rural Development, University of Göttingen, Göttingen, Germany
| | - Christine Kenter
- Institute of Sugar Beet Research at the University of Göttingen, Göttingen, Germany
| | - Carsten Holst
- Department of Agricultural Economics and Rural Development, University of Göttingen, Göttingen, Germany
| | - Bernward Märländer
- Institute of Sugar Beet Research at the University of Göttingen, Göttingen, Germany
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Vaghefi N, Kikkert JR, Bolton MD, Hanson LE, Secor GA, Nelson SC, Pethybridge SJ. Global genotype flow in Cercospora beticola populations confirmed through genotyping-by-sequencing. PLoS One 2017; 12:e0186488. [PMID: 29065114 PMCID: PMC5655429 DOI: 10.1371/journal.pone.0186488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 10/01/2017] [Indexed: 11/18/2022] Open
Abstract
Genotyping-by-sequencing (GBS) was conducted on 333 Cercospora isolates collected from Beta vulgaris (sugar beet, table beet and swiss chard) in the USA and Europe. Cercospora beticola was confirmed as the species predominantly isolated from leaves with Cercospora leaf spot (CLS) symptoms. However, C. cf. flagellaris also was detected at a frequency of 3% in two table beet fields in New York. Resolution of the spatial structure and identification of clonal lineages in C. beticola populations using genome-wide single nucleotide polymorphisms (SNPs) obtained from GBS was compared to genotyping using microsatellites. Varying distance thresholds (bitwise distance = 0, 1.854599 × 10-4, and 1.298 × 10-3) were used for delineation of clonal lineages in C. beticola populations. Results supported previous reports of long distance dispersal of C. beticola through genotype flow. The GBS-SNP data set provided higher resolution in discriminating clonal lineages; however, genotype identification was impacted by filtering parameters and the distance threshold at which the multi-locus genotypes (MLGs) were contracted to multi-locus lineages. The type of marker or different filtering strategies did not impact estimates of population differentiation and structure. Results emphasize the importance of robust filtering strategies and designation of distance thresholds for delineating clonal lineages in population genomics analyses that depend on individual assignment and identification of clonal lineages. Detection of recurrent clonal lineages shared between the USA and Europe, even in the relaxed-filtered SNP data set and with a conservative distance threshold for contraction of MLGs, provided strong evidence for global genotype flow in C. beticola populations. The implications of intercontinental migration in C. beticola populations for CLS management are discussed.
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Affiliation(s)
- Niloofar Vaghefi
- School of Integrative Plant Science, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, New York, United States of America
| | - Julie R. Kikkert
- Cornell Cooperative Extension, Canandaigua, New York, United States of America
| | - Melvin D. Bolton
- United States Department of Agriculture–Agricultural Research Service (USDA-ARS), Red River Valley Agricultural Research Center, Fargo, North Dakota, United States of America
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, United States of America
| | - Linda E. Hanson
- USDA-ARS, Sugar Beet and Bean Research Unit, Michigan State University, Michigan, United States of America
| | - Gary A. Secor
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, United States of America
| | - Scot C. Nelson
- College of Tropical Agriculture and Human Resources, Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Sarah J. Pethybridge
- School of Integrative Plant Science, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, New York, United States of America
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17
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Vaghefi N, Nelson SC, Kikkert JR, Pethybridge SJ. Genetic structure of Cercospora beticola populations on Beta vulgaris in New York and Hawaii. Sci Rep 2017; 7:1726. [PMID: 28496148 PMCID: PMC5431814 DOI: 10.1038/s41598-017-01929-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/03/2017] [Indexed: 11/09/2022] Open
Abstract
Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major disease of Beta vulgaris worldwide. No sexual stage is known for C. beticola but in its asexual form it overwinters on infected plant debris as pseudostromata, and travels short distances by rain splash-dispersed conidiospores. Cercospora beticola infects a broad range of host species and may be seedborne. The relative contribution of these inoculum sources to CLS epidemics on table beet is not well understood. Pathogen isolates collected from table beet, Swiss chard and common lambsquarters in mixed-cropping farms and monoculture fields in New York and Hawaii, USA, were genotyped (n = 600) using 12 microsatellite markers. All isolates from CLS symptoms on lambsquarters were identified as C. chenopodii. Sympatric populations of C. beticola derived from Swiss chard and table beet were not genetically differentiated. Results suggested that local (within field) inoculum sources may be responsible for the initiation of CLS epidemics in mixed-cropping farms, whereas external sources of inoculum may be contributing to CLS epidemics in the monoculture fields in New York. New multiplex PCR assays were developed for mating-type determination for C. beticola. Implications of these findings for disease management are discussed.
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Affiliation(s)
- Niloofar Vaghefi
- School of Integrative Plant Science, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY, 14456, USA
| | - Scot C Nelson
- College of Tropical Agriculture and Human Resources, Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, Honolulu, HI, 96822, USA
| | | | - Sarah J Pethybridge
- School of Integrative Plant Science, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY, 14456, USA.
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18
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De novo genome assembly of Cercospora beticola for microsatellite marker development and validation. FUNGAL ECOL 2017. [DOI: 10.1016/j.funeco.2017.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kimber RBE, Paull JG, Scott ES, Dyson CB, Davidson JA. Temporal and Spatial Development of Cercospora Leaf Spot of Faba Bean Influenced by In Situ Inoculum. PLANT DISEASE 2016; 100:1823-1830. [PMID: 30682975 DOI: 10.1094/pdis-12-14-1264-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The temporal and spatial dynamics of Cercospora leaf spot on susceptible and resistant lines of faba bean grown in or at defined distances from soil with residues infested by Cercospora zonata were examined in South Australia in 2005 and 2006. The disease was first observed on susceptible seedlings 49 days after sowing (DAS) in soil that had been sown with faba bean every 3 years since 1997 (positive soil zone for C. zonata) but was delayed by 1 week in adjacent soil (0 to 16 m away) with no history of cultivation of faba bean (negative soil zone). The incidence of diseased seedlings from 49 to 63 DAS showed a gradient from 4 to 16 m from the infested soil and was significantly greater for susceptible plants grown in the positive versus negative soil zones in field trials conducted in 2005 and 2006 (92 versus 30% in 2005, χ21 = 32.2, P < 0.001; 98 versus 55% in 2006, χ21 = 12.1, P < 0.001). The incidence of Cercospora leaf spot on the resistant line 1322/2 was significantly less (χ26 = 171.7; P < 0.001) than on the susceptible line 'Farah' at that time in both years, with fewer than 5% of the seedlings showing the disease. However, a gradient was shown at 70 to 84 DAS, where disease incidence was significantly greater on line 1322/2 in the positive soil zone than on plants in the negative soil zone in both years (62 and 18%, respectively, with χ21 = 27.9, P < 0.001 in the 2005 trial; and 47 and 6%, respectively, with χ21 = 33.3, P < 0.001 in the 2006 trial). At peak disease severity on Farah, Cercospora leaf spot mean leaf area diseased (%LAD) was severe (85 ± 4.3%) on leaves of the three nodes closest to the soil surface, and much less severe (1 ± 0.6%) in the upper canopy. Defoliation combined with %LAD was used to describe the loss of photosynthetic leaf area (%LPLA) in both cultivars, on both soil zones, in each year. Nonlinear regression analyses using a logistic model described disease development over time on susceptible plants grown in infested soil (e.g., for +12-m blocks within infested soil, y = 2.66 + 46.08/[1 + exp(-0.23 × [X - 40.92])] in 2005 and y = 0.49 + 5.02/[1 + exp(-0.14 × [X - 28.30])] in 2006, where X = DAS and y = %LPLA, with both regressions significant at P < 0.001), whereas an exponential model (e.g., for -12-m blocks from infested soil, y = 0.23 + 0.77 × 1.04X in 2005 and y = 0.44 + 0.56 × 1.04X in 2006, both at P < 0.001) best described disease gradients with increasing distance from the inoculum source. Paired t tests of %LPLA at 77 and 98 DAS showed significant differences in disease severity in the positive versus negative soil zones and a steep gradient in %LPLA from 0 to 4 m from the inoculum source. The role of infested faba bean residue in survival of C. zonata over time was also examined using a pot-bioassay and in situ field assay. When residues were removed from the soil surface or depleted rapidly by animal grazing, the amount of C. zonata inoculum in the soil was significantly less (P < 0.001) than for soil with residue remaining on the soil surface. C. zonata survived in soil and remained infective for at least 30 months after harvest of an infected faba bean crop.
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Affiliation(s)
- R B E Kimber
- South Australian Research and Development Institute (SARDI), Plant Health & Biosecurity, Adelaide, SA 5001, Australia; and School of Agriculture, Food & Wine, University of Adelaide, Waite Campus, SA, Australia
| | - J G Paull
- School of Agriculture, Food & Wine, University of Adelaide, Australia
| | - E S Scott
- School of Agriculture, Food & Wine, University of Adelaide, Australia
| | - C B Dyson
- SARDI, Plant Health & Biosecurity, Adelaide
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Vaghefi N, Hay FS, Kikkert JR, Pethybridge SJ. Genotypic Diversity and Resistance to Azoxystrobin of Cercospora beticola on Processing Table Beet in New York. PLANT DISEASE 2016; 100:1466-1473. [PMID: 30686198 DOI: 10.1094/pdis-09-15-1014-re] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (QOI) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer QOI resistance in fungi. High allelic diversity (He = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC50) > 0.2 μg/ml. The G143A mutation, known to cause QOI resistance in C. beticola, was found in isolates with EC50 values between 0.207 and 19.397 μg/ml. A single isolate with an EC50 of 0.272 μg/ml carried the F129L mutation, known to be associated with low levels of QOI resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.
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Affiliation(s)
- Niloofar Vaghefi
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
| | - Frank S Hay
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
| | | | - Sarah J Pethybridge
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
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21
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Bolton MD, Ebert MK, Faino L, Rivera-Varas V, de Jonge R, Van de Peer Y, Thomma BPHJ, Secor GA. RNA-sequencing of Cercospora beticola DMI-sensitive and -resistant isolates after treatment with tetraconazole identifies common and contrasting pathway induction. Fungal Genet Biol 2016; 92:1-13. [PMID: 27112724 DOI: 10.1016/j.fgb.2016.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 04/18/2016] [Accepted: 04/21/2016] [Indexed: 11/25/2022]
Abstract
Cercospora beticola causes Cercospora leaf spot of sugar beet. Cercospora leaf spot management measures often include application of the sterol demethylation inhibitor (DMI) class of fungicides. The reliance on DMIs and the consequent selection pressures imposed by their widespread use has led to the emergence of resistance in C. beticola populations. Insight into the molecular basis of tetraconazole resistance may lead to molecular tools to identify DMI-resistant strains for fungicide resistance management programs. Previous work has shown that expression of the gene encoding the DMI target enzyme (CYP51) is generally higher and inducible in DMI-resistant C. beticola field strains. In this study, we extended the molecular basis of DMI resistance in this pathosystem by profiling the transcriptional response of two C. beticola strains contrasting for resistance to tetraconazole. A majority of the genes in the ergosterol biosynthesis pathway were induced to similar levels in both strains with the exception of CbCyp51, which was induced several-fold higher in the DMI-resistant strain. In contrast, a secondary metabolite gene cluster was induced in the resistance strain, but repressed in the sensitive strain. Genes encoding proteins with various cell membrane fortification processes were induced in the resistance strain. Site-directed and ectopic mutants of candidate DMI-resistance genes all resulted in significantly higher EC50 values than the wild-type strain, suggesting that the cell wall and/or membrane modified as a result of the transformation process increased resistance to tetraconazole. Taken together, this study identifies important cell membrane components and provides insight into the molecular events underlying DMI resistance in C. beticola.
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Affiliation(s)
- Melvin D Bolton
- USDA - ARS, Northern Crop Science Laboratory, Fargo, ND, USA; North Dakota State University, Department of Plant Pathology, Fargo, ND, USA.
| | - Malaika K Ebert
- USDA - ARS, Northern Crop Science Laboratory, Fargo, ND, USA; North Dakota State University, Department of Plant Pathology, Fargo, ND, USA; Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands
| | - Luigi Faino
- Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands
| | | | - Ronnie de Jonge
- Department of Plant Systems Biology, VIB, Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent Belgium
| | - Yves Van de Peer
- Department of Plant Systems Biology, VIB, Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent Belgium
| | - Bart P H J Thomma
- Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands
| | - Gary A Secor
- North Dakota State University, Department of Plant Pathology, Fargo, ND, USA
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22
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Jacobs A, Auburger S, Bahrs E, Brauer-Siebrecht W, Buchholz M, Christen O, Götze P, Koch HJ, Mußhoff O, Pelka N, Rücknagel J, Märländer B. Die Zuckerrübe als Energiepflanze in Fruchtfolgen auf hoch produktiven Standorten – eine pflanzenbaulich/ ökonomische Systemanalyse. SUGAR INDUSTRY-ZUCKERINDUSTRIE 2014. [DOI: 10.36961/si15272] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Das Verbundprojekt untersucht Fruchtfolgen mit und ohne Zuckerrüben (ZR) bzw. Silomais (SM) in Kombination mit Winterweizen (WW). Produktionsziel für ZR und SM ist Biogas, für WW Backweizen. Ziel ist es, Handlungsempfehlungen für einen nachhaltigen Anbau von Energiefrüchten in abwechslungsreichen Fruchtfolgen abzuleiten. Hierzu werden Erträge, Krankheiten und Schädlinge, Pflanzenschutzmitteleinsatz, N-Bilanz, Humusreproduktion, Bodenstruktur, Energie- und Treibhausgasbilanz, Umweltwirkungen, einzelbetriebliche Wettbewerbsfähigkeit sowie betroffene Agrarmärkte und Standortvorzüglichkeiten bewertet. Datengrundlage bilden vier mehrjährige Feldversuche an drei hoch produktiven Standorten in Deutschland (Harste, Straubing, Etzdorf). Erste Auswertungen (2011, 2012) zeigten hohe Methanhektarerträge (Harste und Straubing) und Netto-Energiegewinne (nur Straubing) aus ZR (6870 Nm3 ha–1 a–1 bzw. 279 GJ ha–1 a–1). Diese lagen jedoch unter denen von SM (8259 Nm3 ha–1 a–1 bzw.
323 GJ ha–1 a–1). Erste Bodenstrukturuntersuchungen (nur Harste, 2012) zeigten ungünstigere Verhältnisse (z.B. Luftkapazität) in der Oberkrume unter Daueranbau von ZR und SM im Vergleich zum WW-Daueranbau. Ertragsschwankungen zwischen Untersuchungsjahren sowie Fruchtfolgen bedürfen weiterer Untersuchungen und detaillierter betriebswirtschaftlicher Bewertungen. In einer bundesweiten Analyse wurde ein ca. 1 Mio. ha hohes, bislang nicht für den ZR-Anbau genutztes Flächenpotenzial für den Anbau von ZR zur Biogasproduktion deutlich.
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23
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Bolton MD, Birla K, Rivera-Varas V, Rudolph KD, Secor GA. Characterization of CbCyp51 from field isolates of Cercospora beticola. PHYTOPATHOLOGY 2012; 102:298-305. [PMID: 22085297 DOI: 10.1094/phyto-07-11-0212] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The hemibiotrophic fungus Cercospora beticola causes leaf spot of sugar beet. Leaf spot control measures include the application of sterol demethylation inhibitor (DMI) fungicides. However, reduced sensitivity to DMIs has been reported recently in the Red River Valley sugar beet-growing region of North Dakota and Minnesota. Here, we report the cloning and molecular characterization of CbCyp51, which encodes the DMI target enzyme sterol P450 14α-demethylase in C. beticola. CbCyp51 is a 1,632-bp intron-free gene with obvious homology to other fungal Cyp51 genes and is present as a single copy in the C. beticola genome. Five nucleotide haplotypes were identified which encoded three amino acid sequences. Protein variant 1 composed 79% of the sequenced isolates, followed by protein variant 2 that composed 18% of the sequences and a single isolate representative of protein variant 3. Because resistance to DMIs can be related to polymorphism in promoter or coding sequences, sequence diversity was assessed by sequencing >2,440 nucleotides encompassing CbCyp51 coding and flanking regions from isolates with varying EC(50) values (effective concentration to reduce growth by 50%) to DMI fungicides. However, no mutations or haplotypes were associated with DMI resistance or sensitivity. No evidence for alternative splicing or differential methylation of CbCyp51 was found that might explain reduced sensitivity to DMIs. However, CbCyp51 was overexpressed in isolates with high EC(50) values compared with isolates with low EC(50) values. After exposure to tetraconazole, isolates with high EC(50) values responded with further induction of CbCyp51, with a positive correlation of CbCyp51 expression and tetraconazole concentration up to 2.5 μg ml(-1).
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Affiliation(s)
- Melvin D Bolton
- United States Department of Agriculture-Agricultural Research Service, Northern Crop Science Laboratory, Fargo, ND, USA.
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24
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Bolton MD, Secor GA, Rivera V, Weiland JJ, Rudolph K, Birla K, Rengifo J, Campbell LG. Evaluation of the potential for sexual reproduction in field populations of Cercospora beticola from USA. Fungal Biol 2012; 116:511-21. [PMID: 22483049 DOI: 10.1016/j.funbio.2012.01.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/19/2012] [Accepted: 01/24/2012] [Indexed: 02/04/2023]
Abstract
Cercospora leaf spot, caused by the hemibiotrophic fungal pathogen Cercospora beticola, is the most economically damaging foliar disease of sugarbeet worldwide. Although most C. beticola populations display characteristics reminiscent of sexual recombination, no teleomorph has been described. To assess whether populations in northern United States have characteristics consistent with sexual reproduction, 1024 isolates collected over a 3-y period were analyzed for frequency and distribution of mating type genes. After clone correction, an approximately equal distribution of mating types was found for each sampling year. Mating type frequency was also assessed in individual lesions. Lesions always consisted of isolates with a single mating type and microsatellite haplotype, but both mating types and up to five microsatellite haplotypes could be found on an individual leaf. The MAT1-1-1 and MAT1-2-1 genes were sequenced from 28 MAT1-1 and 28 MAT1-2 isolates, respectively. Three MAT1-1-1 nucleotide haplotypes were identified that encoded a single amino acid sequence. For MAT1-2-1, five nucleotide haplotypes were identified that encoded four protein variants. MAT1-1-1 and MAT1-2-1 gene expression analyses were conducted on plants inoculated with either or both mating types. MAT1-1-1 expression remained low, but MAT1-2-1 spiked during late stages of colonization. A segment of the MAT1-2-1 coding sequence was also found in MAT1-1 isolates. Taken together, these results suggest that C. beticola has the potential for sexual reproduction.
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Affiliation(s)
- Melvin D Bolton
- United States Department of Agriculture - Agricultural Research Service, Northern Crops Science Laboratory, Fargo, ND 58102-2765, USA.
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25
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Lartey RT, Caesar-TonThat TC, Lenssen AW, Eckhoff J, Hanson SL, Evans RG. Direct Polymerase Chain Reaction-Based Detection of Cercospora beticola in Field Soils. PLANT DISEASE 2010; 94:1100-1104. [PMID: 30743727 DOI: 10.1094/pdis-94-9-1100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cercospora beticola, the causal agent of Cercospora leaf spot of sugar beet, survives as pseudostromata in infected sugar beet residues in the soil. Under optimal conditions, overwintering propagules germinate and produce conidia that are dispersed as primary inoculum to initiate infection in sugar beet. We developed a polymerase chain reaction (PCR) technique for rapid detection of C. beticola in field soils. Total DNA was first isolated from soil amended with C. beticola culture using the PowerSoil DNA Kit. The purified DNA was subjected to PCR in Extract-N-Amp PCR mix with CBACTIN primers over 35 cycles. The amplified products were resolved and compared by electrophoresis in 1% agarose gels. The PCR fragment size of C. beticola from the amended field soil correlated in size with the amplicon from control C. beticola culture DNA extract. Additionally, sample soils were collected from sugar beet fields near Sidney, MT and Foxholm, ND. Total DNA was extracted from the samples and subjected to PCR and resolved as previously described. The amplicons were purified from the gels and subjected to BigDye Terminator Cycle sequencing. All sequences from field soils samples, C. beticola-amended field soil, and pure culture were compared by alignment with a C. beticola actin gene sequence from GenBank. The result of the alignment confirmed the amplicons as products from C. beticola. Rapid screening for the presence of C. beticola in the soil by PCR will improve research capabilities in biological control, disease forecasting, and management of this very important sugar beet pathogen.
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Affiliation(s)
- R T Lartey
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Northern Plains Agricultural Laboratory, Sidney, MT 59270
| | - T C Caesar-TonThat
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Northern Plains Agricultural Laboratory, Sidney, MT 59270
| | - A W Lenssen
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Northern Plains Agricultural Laboratory, Sidney, MT 59270
| | - J Eckhoff
- Montana State University, Eastern Ag Research Center, Sidney 59270
| | - S L Hanson
- USDA-ARS, Northern Plains Agricultural Laboratory
| | - R G Evans
- USDA-ARS, Northern Plains Agricultural Laboratory
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26
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Khan J, Qi A, Khan MFR. Fluctuations in number of Cercospora beticola conidia in relationship to environment and disease severity in sugar beet. PHYTOPATHOLOGY 2009; 99:796-801. [PMID: 19522577 DOI: 10.1094/phyto-99-7-0796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Cercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P < 0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.
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Affiliation(s)
- J Khan
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, USA
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