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Garrido PA, Proaño-Cuenca F, Flor FJF, Benítez EAD, Torres IFS, Kaiser ARK, Sain L, Peñaloza YAM, Marek SM, Melouk H, Daughtrey M, Garzon CD. Identification and Characterization of Pythium, Globisporangium, and Phytopythium Species Present in Floricultural Crops from Long Island, New York. PHYTOPATHOLOGY 2023; 113:1335-1346. [PMID: 36510360 DOI: 10.1094/phyto-06-22-0195-r] [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: 06/17/2023]
Abstract
Several Pythium, Globisporangium, and Phytopythium species cause Pythium diseases in greenhouse floricultural crops, resulting in significant seasonal losses. Four hundred and eighteen Pythium, Globisporangium, and Phytopythium isolates from flowering crops, growing media, or bench and floor debris were collected from Long Island greenhouses or clinic samples between 2002 and 2013. Isolates were identified to species based on morphology and internal transcribed spacer barcoding. Twenty-two species of Pythium, Phytopythium, and Globisporangium were identified, with Globisporangium irregulare sensu lato (s.l.) being the most common. To determine the origin of inoculum during the 2011 cropping season, 11 microsatellite loci were analyzed in 124 G. irregulare s.l. isolates collected in four greenhouses and six previously collected from clinic samples. Cluster analyses grouped G. irregulare s.l. isolates into four groups: G. irregulare sensu stricto, plus three G. cryptoirregulare clusters. The population structure defined by greenhouse and host was found in two clades. Additionally, the population dynamics of G. irregulare s.l. isolates associated with Pelargonium spp. from 2011 to 2013 were examined using 85 isolates and nine informative microsatellite loci to assess inoculum survival over multiple cropping seasons. Although most isolates had unique genotypes, closely related genotypes were found in the same locations over different years. Our results indicate that G. irregulare s.l. inocula have local as well as remote origins. Isolates may be initially brought into ornamental operations from common sources, such as infected plant materials or infested potting mixes. Our results support the hypothesis that established strains can serve as inocula and survive in greenhouse facilities over multiple seasons.
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Affiliation(s)
- Patricia A Garrido
- Centro de Investigación de Alimentos, CIAL, Facultad de Ciencias de la Ingeniería e Industrias, Universidad UTE, Quito, Ecuador
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
| | - Fernanda Proaño-Cuenca
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
| | - Francisco J Flores Flor
- Centro de Investigación de Alimentos, CIAL, Facultad de Ciencias de la Ingeniería e Industrias, Universidad UTE, Quito, Ecuador
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
- Microbiology and Environmental Research Team, Departamento de Ciencias de la Vida, Universidad de las Fuerzas Armadas-ESPE, Sangolquí, Ecuador
| | - Edinson A Díaz Benítez
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
- Facultad de Ciencias Agrarias y del Ambiente, Universidad Francisco de Paula Santander, Cúcuta, Colombia
| | - Ivanna F Sánchez Torres
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
- Microbiology and Environmental Research Team, Departamento de Ciencias de la Vida, Universidad de las Fuerzas Armadas-ESPE, Sangolquí, Ecuador
| | - Alma R Koch Kaiser
- Microbiology and Environmental Research Team, Departamento de Ciencias de la Vida, Universidad de las Fuerzas Armadas-ESPE, Sangolquí, Ecuador
| | - Linda Sain
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
| | - Yaneth Amparo Muñoz Peñaloza
- Plant Pathology and Plant-Microbe Biology Section, Long Island Horticultural Research and Extension Center, Cornell University, Riverhead, NY 11901, U.S.A
| | - Stephen M Marek
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
| | - Hassan Melouk
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
| | - Margery Daughtrey
- Plant Pathology and Plant-Microbe Biology Section, Long Island Horticultural Research and Extension Center, Cornell University, Riverhead, NY 11901, U.S.A
| | - Carla D Garzon
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, U.S.A
- Department of Plant Science and Landscape Architecture, Delaware Valley University, Doylestown, PA 18901, U.S.A
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Alotaibi NM, Saeed M, Alshammari N, Alabdallah NM, Mahfooz S. Comparative genomics reveals the presence of simple sequence repeats in genes related to virulence in plant pathogenic Pythium ultimum and Pythium vexans. Arch Microbiol 2023; 205:256. [PMID: 37270724 DOI: 10.1007/s00203-023-03595-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/08/2023] [Accepted: 05/21/2023] [Indexed: 06/05/2023]
Abstract
In this study, we evaluated the occurrence, relative abundance (RA), and density (RD) of simple sequence repeats (SSRs) in the complete genome and transcriptomic sequences of the plant pathogenic species of Pythium to acquire a better knowledge of their genome structure and evolution. Among the species, P. ultimum had the highest RA and RD of SSRs in the genomic sequences, whereas P. vexans had the highest RA and RD in the transcriptomic sequences. The genomic and transcriptomic sequences of P. aphanidermatum showed the lowest RA and RD of SSRs. Trinucleotide SSRs were the most prevalent class in both genomic and transcriptomic sequences, while dinucleotide SSRs were the least prevalent. The G + C content of the transcriptomic sequences was found to be positively correlated with the number (r = 0.601) and RA (r = 0.710) of SSRs. A motif conservation study revealed the highest number of unique motifs in P. vexans (9.9%). Overall, a low conservation of motifs was observed among the species (25.9%). A gene enrichment study revealed P. vexans and P. ultimum carry SSRs in their genes that are directly connected to virulence, whereas the remaining two species, P. aphanidermatum and P. arrhenomanes, harbour SSRs in genes involved in transcription, translation, and ATP binding. In an effort to enhance the genomic resources, a total of 11,002 primers from the transcribed regions were designed for the pathogenic Pythium species. Furthermore, the unique motifs identified in this work could be employed as molecular probes for species identification.
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Affiliation(s)
- Nahaa M Alotaibi
- Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh, 11671, Saudi Arabia
| | - Mohd Saeed
- Department of Biology, College of Science, University of Hail, Hail, 2440, Saudi Arabia
| | - Nawaf Alshammari
- Department of Biology, College of Science, University of Hail, Hail, 2440, Saudi Arabia
| | - Nadiyah M Alabdallah
- Department of Biology, College of Science, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam, 31441, Saudi Arabia
- Basic and Applied Scientific Research Centre, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam, 31441, Saudi Arabia
| | - Sahil Mahfooz
- Department of Biotechnology, V.B.S. Purvanchal University, Jaunpur, Uttar Pradesh, 222003, India.
- , The Academic Editors, Saryu Enclave, Awadh Vikas Yojna, Lucknow, 226002, India.
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Ma M, Taylor PWJ, Chen D, Vaghefi N, He JZ. Major Soilborne Pathogens of Field Processing Tomatoes and Management Strategies. Microorganisms 2023; 11:microorganisms11020263. [PMID: 36838227 PMCID: PMC9958975 DOI: 10.3390/microorganisms11020263] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/28/2022] [Accepted: 12/28/2022] [Indexed: 01/20/2023] Open
Abstract
Globally, tomato is the second most cultivated vegetable crop next to potato, preferentially grown in temperate climates. Processing tomatoes are generally produced in field conditions, in which soilborne pathogens have serious impacts on tomato yield and quality by causing diseases of the tomato root system. Major processing tomato-producing countries have documented soilborne diseases caused by a variety of pathogens including bacteria, fungi, nematodes, and oomycetes, which are of economic importance and may threaten food security. Recent field surveys in the Australian processing tomato industry showed that plant growth and yield were significantly affected by soilborne pathogens, especially Fusarium oxysporum and Pythium species. Globally, different management methods have been used to control diseases such as the use of resistant tomato cultivars, the application of fungicides, and biological control. Among these methods, biocontrol has received increasing attention due to its high efficiency, target-specificity, sustainability and public acceptance. The application of biocontrol is a mix of different strategies, such as applying antagonistic microorganisms to the field, and using the beneficial metabolites synthesized by these microorganisms. This review provides a broad review of the major soilborne fungal/oomycete pathogens of the field processing tomato industry affecting major global producers, the traditional and biological management practices for the control of the pathogens, and the various strategies of the biological control for tomato soilborne diseases. The advantages and disadvantages of the management strategies are discussed, and highlighted is the importance of biological control in managing the diseases in field processing tomatoes under the pressure of global climate change.
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Talaromyces variabilis interferes with Pythium aphanidermatum growth and suppresses Pythium-induced damping-off of cucumbers and tomatoes. Sci Rep 2019; 9:11255. [PMID: 31375723 PMCID: PMC6677756 DOI: 10.1038/s41598-019-47736-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 07/23/2019] [Indexed: 01/17/2023] Open
Abstract
Pythium-induced damping-off disease is a major disease limiting cucumber and tomato production in different parts of the world. The current study investigated the efficiency of Talaromyces variabilis and its bioactive metabolites in suppressing Pythium-induced damping-off of cucumbers and tomatoes. T. variabilis inhibited the in vitro growth of P. aphanidermatum in solid and liquid media. In addition, abnormalities in P. aphanidermatum hyphae were observed as a result of T. variabilis. Extracts from T. variabilis induced cellular leakage and suppressed oospore production of P. aphanidermatum. Biochemical analyses of T. variabilis metabolites showed that T. variabilis produces glucanase, cellulase and siderophores, suggesting the contribution of these metabolites in the inhibition of P. aphandermatum growth and in hyphal abnormalities. Treating cucumber seeds with spore and mycelial suspension of T. variabilis isolates led to a significant improvement in the seedling survival of P. aphanidermatum-inoculated seedlings from 18 to 52% (improvement by 34%) for isolate 48 P and from 30–66% (improvement by 36%) for isolate 28 R. Similarly, treating tomato seeds with spore and mycelial suspension of T. variabilis isolates led to a significant improvement in the seedling survival of P. aphanidermatum-inoculated seedlings from 7 to 36% (improvement by 29%) for isolate 28 R and from 20 to 64% (improvement by 44%) for isolate 48 P. Differences in the percent improvement in seedling survival between experiments may be related to difference in the efficacy of the two different isolates or their interaction with the hosts and pathogen. The use of T. variabilis in the biocontrol of Pythium-induced diseases may offer alternatives to the currently used chemical control.
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Del Castillo Múnera J, Quesada-Ocampo LM, Rojas A, Chilvers MI, Hausbeck MK. Population Structure of Pythium ultimum from Greenhouse Floral Crops in Michigan. PLANT DISEASE 2019; 103:859-867. [PMID: 30908944 DOI: 10.1094/pdis-03-18-0394-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pythium ultimum causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of P. ultimum in Michigan floriculture crops, simple sequence repeats (SSRs) were developed using the previously published P. ultimum predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers. The average unbiased Simpson's index (λu, 0.95), evenness (E5, 0.56), and recovery of 12 major clones out of the 65 multilocus genotypes obtained, suggests that P. ultimum is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum populations. Finally, the presence of common genotypes among counties suggests that there is an exchange of infected plant material among greenhouse facilities, or that there is a common source of inoculum coming to the region. Continued monitoring of pathogen populations will enhance our understanding of population dynamics of P. ultimum in Michigan and facilitate improvement of control strategies.
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Affiliation(s)
| | | | - Alejandro Rojas
- 3 Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701
| | - Martin I Chilvers
- 4 Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, 48824
| | - Mary K Hausbeck
- 4 Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, 48824
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Huzar-Novakowiski J, Dorrance AE. Genetic Diversity and Population Structure of Pythium irregulare from Soybean and Corn Production Fields in Ohio. PLANT DISEASE 2018; 102:1989-2000. [PMID: 30124360 DOI: 10.1094/pdis-11-17-1725-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: 06/08/2023]
Abstract
High levels of genetic diversity have been described within the Pythium irregulare complex from several host plants; however, little is known about the population structure in fields used for grain production. Therefore, the objective of this study was to evaluate the genetic diversity and population structure of 53 isolates baited from 28 soybean and corn production fields from 25 counties in Ohio. Genetic diversity was characterized based on sequence analysis of the internal transcribed spacer (ITS1-5.8S-ITS2) region and with 21 simple sequence repeat (SSR) markers. In addition, aggressiveness on soybean, optimum growth temperature, and sensitivity to metalaxyl fungicide were determined. ITS sequence analysis indicated that four isolates clustered with P. cryptoirregulare, whereas the remaining isolates clustered with P. irregulare that was subdivided into two groups (1 and 2). Cluster analysis of SSR data revealed a similar subdivision, which was also supported by structure analysis. The isolates from group 2 grew at a slower rate, but both groups of P. irregulare and P. cryptoirregulare recovered in this study had the same optimum growth at 27°C. Variability of aggressiveness and sensitivity toward metalaxyl fungicide was also observed among isolates within each group. The results from this study will help in the selection of isolates to be used in screening for resistance, assessment of fungicide efficacy, and disease management recommendations.
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Affiliation(s)
- J Huzar-Novakowiski
- Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691
| | - A E Dorrance
- Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691
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Woods-Tör A, Studholme DJ, Cevik V, Telli O, Holub EB, Tör M. A Suppressor/Avirulence Gene Combination in Hyaloperonospora arabidopsidis Determines Race Specificity in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2018; 9:265. [PMID: 29545818 PMCID: PMC5838922 DOI: 10.3389/fpls.2018.00265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 02/14/2018] [Indexed: 05/23/2023]
Abstract
The pathosystem of Arabidopsis thaliana and diploid biotrophic oomycete Hyaloperonospora arabidopsidis (Hpa) has been a model for investigating the molecular basis of Flor's gene-for-gene hypothesis. The isolates Hpa-Noks1 and Hpa-Cala2 are virulent on Arabidopsis accession RMX-A02 whilst an F1 generated from a cross between these two isolates was avirulent. The F2 progeny segregated 3,1 (avirulent, virulent), indicating a single major effect AVR locus in this pathogen. SNP-based linkage mapping confirmed a single AVR locus within a 14 kb map interval containing two genes encoding putative effectors. The Hpa-Cala2 allele of one gene, designated H. arabidopsidiscryptic1 (HAC1), encodes a protein with a signal peptide and an RxLR/dEER motif, and triggers a defense response in RMX-A02. The second gene is heterozygous in Hpa-Cala2. One allele, designated Suppressor ofHAC1Cala2 (S-HAC1Cala2 ) encodes a protein with a signal peptide and a dKEE motif with no RxLR motif; the other allele (s-hac1Cala2 ) encodes a protein with a signal peptide, a dEEE motif and is divergent in sequence from the S-HAC1Cala2 allele. In selfed progeny from Hpa-Cala2, dominant S-HAC1Cala2 allele carrying progeny correlates with virulence in RMX-A02, whereas homozygous recessive s-hac1Cala2 carrying progeny were avirulent. Genetic investigations suggested other heterozygous suppressor loci might exist in the Hpa-Cala2 genome.
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Affiliation(s)
- Alison Woods-Tör
- Institute of Science and the Environment, University of Worcester, Worcester, United Kingdom
| | - David J. Studholme
- College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Volkan Cevik
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Osman Telli
- Institute of Science and the Environment, University of Worcester, Worcester, United Kingdom
| | - Eric B. Holub
- Warwick Crop Centre, School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Mahmut Tör
- Institute of Science and the Environment, University of Worcester, Worcester, United Kingdom
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Weiland JE, Garrido P, Kamvar ZN, Espíndola AS, Marek SM, Grünwald NJ, Garzón CD. Population Structure of Pythium irregulare, P. ultimum, and P. sylvaticum in Forest Nursery Soils of Oregon and Washington. PHYTOPATHOLOGY 2015; 105:684-694. [PMID: 25607720 DOI: 10.1094/phyto-05-14-0147-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Pythium species are important soilborne pathogens occurring in the forest nursery industry of the Pacific Northwest. However, little is known about their genetic diversity or population structure and it is suspected that isolates are moved among forest nurseries on seedling stock and shared field equipment. In order to address these concerns, a total of 115 isolates of three Pythium species (P. irregulare, P. sylvaticum, and P. ultimum) were examined at three forest nurseries using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. Analyses revealed distinct patterns of intraspecific variation for the three species. P. sylvaticum exhibited the most diversity, followed by P. irregulare, while substantial clonality was found in P. ultimum. For both P. irregulare and P. sylvaticum, but not P. ultimum, there was evidence for significant variation among nurseries. However, all three species also exhibited at least two distinct lineages not associated with the nursery of origin. Finally, evidence was found that certain lineages and clonal genotypes, including fungicide-resistant isolates, are shared among nurseries, indicating that pathogen movement has occurred.
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Affiliation(s)
- Jerry E Weiland
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Patricia Garrido
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Zhian N Kamvar
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Andrés S Espíndola
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Stephen M Marek
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Niklaus J Grünwald
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Carla D Garzón
- First and sixth authors: U.S. Department of Agriculture-Agriculture Research Service, Horticultural Crops Research Laboratory, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; second, fourth, fifth, and seventh authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74074; and third author: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
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Schroeder KL, Martin FN, de Cock AWAM, Lévesque CA, Spies CFJ, Okubara PA, Paulitz TC. Molecular Detection and Quantification of Pythium Species: Evolving Taxonomy, New Tools, and Challenges. PLANT DISEASE 2013; 97:4-20. [PMID: 30722255 DOI: 10.1094/pdis-03-12-0243-fe] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The genus Pythium is one of the most important groups of soilborne plant pathogens, present in almost every agricultural soil and attacking the roots of thousands of hosts, reducing crop yield and quality. Most species are generalists, necrotrophic pathogens that infect young juvenile tissue. In fact, Cook and Veseth have called Pythium the "common cold" of wheat, because of its chronic nature and ubiquitous distribution. Where Pythium spp. are the cause of seedling damping-off or emergence reduction, the causal agent can easily be identified based on symptoms and culturing. In more mature plants, however, infection by Pythium spp. is more difficult to diagnose, because of the nonspecific symptoms that could have abiotic causes such as nutrient deficiencies or be due to other root rotting pathogens. Molecular methods that can accurately identify and quantify this important group are needed for disease diagnosis and management recommendations and to better understand the epidemiology and ecology of this important group. The purpose of this article is to outline the current state-of-the-art in the detection and quantification of this important genus. In addition, we will introduce the reader to new changes in the taxonomy of this group.
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Affiliation(s)
| | | | | | - C André Lévesque
- Agriculture and Agri-Food Canada, Central Experimental Farm, Ottawa, ON
| | | | - Patricia A Okubara
- USDA-ARS, Root Disease and Biological Control Research Unit, Pullman, WA
| | - Timothy C Paulitz
- USDA-ARS, Root Disease and Biological Control Research Unit, Pullman, WA
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Al-Sadi AM, Al-Ghaithi AG, Al-Balushi ZM, Al-Jabri AH. Analysis of Diversity in Pythium aphanidermatum Populations from a Single Greenhouse Reveals Phenotypic and Genotypic Changes over 2006 to 2011. PLANT DISEASE 2012; 96:852-858. [PMID: 30727347 DOI: 10.1094/pdis-07-11-0624] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A study was conducted to investigate phenotypic and genotypic changes within Pythium aphanidermatum populations during the period 2006 to 2011. In total, 92 isolates of P. aphanidermatum (59 in 2006 and 33 in 2011) were obtained from different planting sites (soil) of cucumber from a single greenhouse. Generated sequences of the internal transcribed spacer (ITS) ribosomal DNA showed that all, except one isolate, share an identical sequence of the ITS region. Most (89%) P. aphanidermatum isolates were found to be aggressive on cucumber seedlings, with no significant differences in the aggressiveness level between populations obtained from different planting rows or different years. Sensitivity to metalaxyl among populations of P. aphanidermatum increased significantly from concentration resulting in 50% growth inhibition levels of 0.070 to 1.823 (average 0.824 μg ml-1) in 2006 to 0.002 to 0.564 (average 0.160 μg ml-1) in 2011. Amplified fragment length polymorphism analysis of the 92 isolates produced 92 different genotypes and 985 polymorphic loci. P. aphanidermatum populations from 2006 and 2011 were found to have low levels of genetic diversity (H = 0.1425), which implies introduction of the isolates into the greenhouse via common sources. Results from analysis of molecular variance (FST = 0.0307 in 2006 and 0.0222 in 2011) provided evidence for frequent exchange of Pythium inoculum between different planting locations within the same year. However, the analysis showed moderate levels (FST = 0.1731) of genetic differentiation among populations from the 2 years. This was supported by unweighted pair group method with arithmetic means analysis, which showed clustering of many of the 2006 isolates in separate clusters. The change in the metalaxyl sensitivity of the populations from 2006 to 2011 accompanied by the genetic differences among these two populations may suggest that many of the isolates from 2006 were lost and were replaced by new and highly sensitive P. aphanidermatum isolates by 2011.
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Affiliation(s)
- A M Al-Sadi
- Department of Crop Sciences, Sultan Qaboos University, Al Khod 123, Sultanate of Oman
| | - A G Al-Ghaithi
- Department of Crop Sciences, Sultan Qaboos University, Al Khod 123, Sultanate of Oman
| | - Z M Al-Balushi
- Department of Crop Sciences, Sultan Qaboos University, Al Khod 123, Sultanate of Oman
| | - A H Al-Jabri
- Department of Crop Sciences, Sultan Qaboos University, Al Khod 123, Sultanate of Oman
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Zoosporic true fungi and heterotrophic straminipiles assemblages from soil of Brazilian Cerrado areas. FUNGAL ECOL 2012. [DOI: 10.1016/j.funeco.2011.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Yang C, Hamel C, Vujanovic V, Gan Y. Fungicide: Modes of Action and Possible Impact on Nontarget Microorganisms. ACTA ACUST UNITED AC 2011. [DOI: 10.5402/2011/130289] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Fungicides have been used widely in order to control fungal diseases and increase crop production. However, the effects of fungicides on microorganisms other than fungi remain unclear. The modes of action of fungicides were never well classified and presented, making difficult to estimate their possible nontarget effects. In this paper, the action modes and effects of fungicides targeting cell membrane components, protein synthesis, signal transduction, respiration, cell mitosis, and nucleic acid synthesis were classified, and their effects on nontarget microorganisms were reviewed. Modes of action and potential non-target effects on soil microorganisms should be considered in the selection of fungicide in order to protect the biological functions of soil and optimize the benefits derived from fungicide use in agricultural systems.
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Affiliation(s)
- Chao Yang
- Semiarid Prairie Agricultural Research Centre, AAFC, Swift Current, SK, Canada S9H 3X2
- Department of Food and Bioproducts Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5N8
| | - Chantal Hamel
- Semiarid Prairie Agricultural Research Centre, AAFC, Swift Current, SK, Canada S9H 3X2
| | - Vladimir Vujanovic
- Department of Food and Bioproducts Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5N8
| | - Yantai Gan
- Semiarid Prairie Agricultural Research Centre, AAFC, Swift Current, SK, Canada S9H 3X2
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