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Aditya S, Aggarwal R, Bashyal BM, Gurjar MS, Saharan MS, Aggarwal S. Unraveling the dynamics of wheat leaf blight complex: isolation, characterization, and insights into pathogen population under Indian conditions. Front Microbiol 2024; 15:1287721. [PMID: 38450160 PMCID: PMC10915091 DOI: 10.3389/fmicb.2024.1287721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Accepted: 01/31/2024] [Indexed: 03/08/2024] Open
Abstract
Wheat, a staple food crop for 35% of the global population, faces a threat from Helminthosporium leaf blight (HLB), a complex of spot blotch (Bipolaris sorokiniana) and tan spot (Pyrenophora-tritici-repentis) diseases under warm and humid conditions. However, in Indian conditions, the knowledge of existing pathogen populations associated with the HLB complex is limited and largely dominated by only B. sorokiniana (spot blotch). To address this, diseased samples were collected from all six wheat growing zones during 2020-2022. The pathogenic species were identified through in-depth morphological characterization, supplemented with ITS-rDNA and GAPDH sequence analysis, a diagnostic SCAR marker, and pathogenicity studies on two wheat varieties: Sonalika and HD2733. The 32 isolates collected from 10 different states consist of B. spicifera (12.5% of all isolates), Exserohilum rostratum (9.3%), Bipolaris oryzae (3.1%), and B. sorokiniana (75%). B. sorokiniana exhibited the highest disease severity on both varieties. Other lesser-known pathogenic species also produced comparable disease severity as B. sorokiniana isolates and, therefore are economically important. Unraveling pathogen composition and biology aids in disease control and resistance breeding. Our study highlights economically impactful and lesser-known pathogenic species causing wheat leaf blight/spot blotch in India, guiding both current management and future resistance breeding strategies in plant pathology.
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Affiliation(s)
- Sanghmitra Aditya
- Fungal Molecular Biology Laboratory, Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Rashmi Aggarwal
- Fungal Molecular Biology Laboratory, Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi, India
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Rogério F, Van Oosterhout C, Ciampi-Guillardi M, Correr FH, Hosaka GK, Cros-Arteil S, Rodrigues Alves Margarido G, Massola Júnior NS, Gladieux P. Means, motive and opportunity for biological invasions: Genetic introgression in a fungal pathogen. Mol Ecol 2023; 32:2428-2442. [PMID: 35076152 DOI: 10.1111/mec.16366] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 01/07/2022] [Accepted: 01/13/2022] [Indexed: 11/28/2022]
Abstract
Invasions by fungal plant pathogens pose a significant threat to the health of agricultural ecosystems. Despite limited standing genetic variation, many invasive fungal species can adapt and spread rapidly, resulting in significant losses to crop yields. Here, we report on the population genomics of Colletotrichum truncatum, a polyphagous pathogen that can infect more than 460 plant species, and an invasive pathogen of soybean in Brazil. We study the whole-genome sequences of 18 isolates representing 10 fields from two major regions of soybean production. We show that Brazilian C. truncatum is subdivided into three phylogenetically distinct lineages that exchange genetic variation through hybridization. Introgression affects 2%-30% of the nucleotides of genomes and varies widely between the lineages. We find that introgressed regions comprise secreted protein-encoding genes, suggesting possible co-evolutionary targets for selection in those regions. We highlight the inherent vulnerability of genetically uniform crops in the agro-ecological environment, particularly when faced with pathogens that can take full advantage of the opportunities offered by an increasingly globalized world. Finally, we discuss "the means, motive and opportunity" of fungal pathogens and how they can become invasive species of crops. We call for more population genomic studies because such analyses can help identify geographical areas and pathogens that pose a risk, thereby helping to inform control strategies to better protect crops in the future.
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Affiliation(s)
- Flávia Rogério
- Department of Plant Pathology and Nematology, University of São Paulo, Piracicaba, SP, Brazil
- Institute for Agribiotechnology Research (CIALE), University of Salamanca, Salamanca, Spain
| | | | - Maisa Ciampi-Guillardi
- Department of Plant Pathology and Nematology, University of São Paulo, Piracicaba, SP, Brazil
| | | | | | | | | | - Nelson S Massola Júnior
- Department of Plant Pathology and Nematology, University of São Paulo, Piracicaba, SP, Brazil
| | - Pierre Gladieux
- UMR PHIM, University of Montpellier, INRAE, CIRAD, Montpellier, France
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Rogério F, Baroncelli R, Cuevas-Fernández FB, Becerra S, Crouch J, Bettiol W, Azcárate-Peril MA, Malapi-Wight M, Ortega V, Betran J, Tenuta A, Dambolena JS, Esker PD, Revilla P, Jackson-Ziems TA, Hiltbrunner J, Munkvold G, Buhiniček I, Vicente-Villardón JL, Sukno SA, Thon MR. Population Genomics Provide Insights into the Global Genetic Structure of Colletotrichum graminicola, the Causal Agent of Maize Anthracnose. mBio 2023; 14:e0287822. [PMID: 36533926 PMCID: PMC9973043 DOI: 10.1128/mbio.02878-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/17/2022] [Indexed: 12/24/2022] Open
Abstract
Understanding the genetic diversity and mechanisms underlying genetic variation in pathogen populations is crucial to the development of effective control strategies. We investigated the genetic diversity and reproductive biology of Colletotrichum graminicola isolates which infect maize by sequencing the genomes of 108 isolates collected from 14 countries using restriction site-associated DNA sequencing (RAD-seq) and whole-genome sequencing (WGS). Clustering analyses based on single-nucleotide polymorphisms revealed three genetic groups delimited by continental origin, compatible with short-dispersal of the pathogen and geographic subdivision. Intra- and intercontinental migration was observed between Europe and South America, likely associated with the movement of contaminated germplasm. Low clonality, evidence of genetic recombination, and high phenotypic diversity were detected. We show evidence that, although it is rare (possibly due to losses of sexual reproduction- and meiosis-associated genes) C. graminicola can undergo sexual recombination. Our results support the hypotheses that intra- and intercontinental pathogen migration and genetic recombination have great impacts on the C. graminicola population structure. IMPORTANCE Plant pathogens cause significant reductions in yield and crop quality and cause enormous economic losses worldwide. Reducing these losses provides an obvious strategy to increase food production without further degrading natural ecosystems; however, this requires knowledge of the biology and evolution of the pathogens in agroecosystems. We employed a population genomics approach to investigate the genetic diversity and reproductive biology of the maize anthracnose pathogen (Colletotrichum graminicola) in 14 countries. We found that the populations are correlated with their geographical origin and that migration between countries is ongoing, possibly caused by the movement of infected plant material. This result has direct implications for disease management because migration can cause the movement of more virulent and/or fungicide-resistant genotypes. We conclude that genetic recombination is frequent (in contrast to the traditional view of C. graminicola being mainly asexual), which strongly impacts control measures and breeding programs aimed at controlling this disease.
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Affiliation(s)
- Flávia Rogério
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Riccardo Baroncelli
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
- Department of Agricultural and Food Sciences (DISTAL), University of Bologna, Bologna, Italy
| | - Francisco Borja Cuevas-Fernández
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sioly Becerra
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - JoAnne Crouch
- Foreign Disease and Weed Science Unit, United States Department of Agriculture, Fort Detrick, Maryland, USA
| | | | - M. Andrea Azcárate-Peril
- Center for Gastrointestinal Biology and Disease, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
- Division of Gastroenterology and Hepatology, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
- UNC Microbiome Core, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Martha Malapi-Wight
- USDA Animal and Plant Health Inspection Services, Biotechnology Regulatory Services, Riverdale, Maryland, USA
| | | | | | - Albert Tenuta
- Ontario Ministry of Agriculture, Food, and Rural Affairs, University of Guelph-Ridgetown, Ridgetown, Ontario, Canada
| | - José S. Dambolena
- Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, IMBIV-CONICET-ICTA, Córdoba, Argentina
| | - Paul D. Esker
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, State College, Pennsylvania, USA
| | - Pedro Revilla
- Misión Biológica de Galicia, Spanish National Research Council (CSIC), Pontevedra, Spain
| | | | | | - Gary Munkvold
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, USA
| | - Ivica Buhiniček
- BC Institute for Breeding and Production of Field Crops, Dugo Selo, Croatia
| | | | - Serenella A. Sukno
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Michael R. Thon
- Instituto de Investigación en Agrobiotecnología (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
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Zhao D, Fan S, Zhang D, Pan Y, Gu Q, Wang J, Yang Z, Zhu J. Parasexual reproduction in Alternaria solani: Simple sequence repeat molecular evidence for haploidization. Mycologia 2021; 113:949-955. [PMID: 34125655 DOI: 10.1080/00275514.2021.1922243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Multiple alleles were constantly detected in Alternaria solani isolates by simple sequence repeat (SSR) analysis, and sectors were also observed in their subcultures. These preliminary results and observations point to a possible parasexual cycle in A. solani. In this study, codominant SSR markers were used as molecular markers on the chromosomes of A. solani and single-conidium subculture was used to simulate the mitosis process of A. solani in nature. The number of alleles at locus As-95236 changed from 2 to 1 as a molecular marker for haploidy of parasexuality of A. solani. Fifty monosporic F1 strains were tested. The results showed that two parent strains lost allele with a haploid probability of 38%. For F2 strains, the results showed that all four F1 strains lost allele with a haploid probability of 75%. Since sexual recombination of A. solani has not been found so far, the allele lost in the subcultures of A. solani isolates provides molecular evidence for the existence of parasexual reproduction in A. solani.
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Affiliation(s)
- Dongmei Zhao
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Shasha Fan
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Dai Zhang
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Yang Pan
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Qing Gu
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Jinhui Wang
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Zhihui Yang
- College of Plant Protection, Hebei Agricultural University, Baoding, China
| | - Jiehua Zhu
- College of Plant Protection, Hebei Agricultural University, Baoding, China
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Mehta N, Baghela A. Quorum sensing-mediated inter-specific conidial anastomosis tube fusion between Colletotrichum gloeosporioides and C. siamense. IMA Fungus 2021; 12:7. [PMID: 33789776 PMCID: PMC8015167 DOI: 10.1186/s43008-021-00058-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 02/21/2021] [Indexed: 02/07/2023] Open
Abstract
Many plant pathogenic filamentous fungi undergo fusion of conidia through conidial anastomosis tubes (CATs), which is believed to facilitate horizontal gene transfer between species. We discovered a remarkable inter-specific CAT fusion between two important plant fungal pathogens Colletotrichum gloeosporioides and C. siamense. In an invitro assay, under no selection pressure, the inter-specific CAT fusion was preferred with higher frequency (25% ± 5%) than intra-specific CAT fusion (11% ± 3.6%). Different stages of CAT fusion viz. CAT induction, homing, and fusion were observed during this inter-specific CAT fusion. The CAT fusion was found to be higher in absence of nutrients and under physiological stresses. This CAT fusion involved a quorum sensing phenomenon, wherein the CAT induction was dependent on conidial density and the putative quorum sensing molecule was extractable in chloroform. Movement of nuclei, mitochondria, and lipid droplets were observed during the CAT fusion. Post CAT fusion, the resulting conidia gave rise to putative heterokaryotic progenies with variable colony characteristics as compared to their parental strains. Few heterokaryons showed variable AFLP banding pattern compared to their parental strains, thereby suggesting a possible genetic exchange between the two species through CAT fusion. The heterokaryotic progenies exhibited varied fitness under different stress conditions. Our study illustrated a possible role of inter-specific CAT fusion in generation of genetic and phenotypic diversity in these fungal pathogens.
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Affiliation(s)
- Nikita Mehta
- National Fungal Culture Collection of India (NFCCI), Biodiversity and Palaeobiology Group, MACS-Agharkar Research Institute, G.G. Agarkar Road, Pune, 411004, India.,Savitribai Phule Pune University, Pune, 411007, India
| | - Abhishek Baghela
- National Fungal Culture Collection of India (NFCCI), Biodiversity and Palaeobiology Group, MACS-Agharkar Research Institute, G.G. Agarkar Road, Pune, 411004, India. .,Savitribai Phule Pune University, Pune, 411007, India.
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da Silva LL, Moreno HLA, Correia HLN, Santana MF, de Queiroz MV. Colletotrichum: species complexes, lifestyle, and peculiarities of some sources of genetic variability. Appl Microbiol Biotechnol 2020; 104:1891-1904. [PMID: 31932894 DOI: 10.1007/s00253-020-10363-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/30/2019] [Accepted: 01/09/2020] [Indexed: 11/25/2022]
Abstract
The genus Colletotrichum comprises species with different lifestyles but is mainly known for phytopathogenic species that infect crops of agronomic relevance causing considerable losses. The fungi of the genus Colletotrichum are distributed in species complexes and within each complex some species have particularities regarding their lifestyle. The most commonly found and described lifestyles in Colletotrichum are endophytic and hemibiotrophic phytopathogenic. Several of these phytopathogenic species show wide genetic variability, which makes long-term maintenance of resistance in plants difficult. Different mechanisms may play an important role in the emergence of genetic variants but are not yet fully understood in this genus. These mechanisms include heterokaryosis, a parasexual cycle, sexual cycle, transposable element activity, and repeat-induced point mutations. This review provides an overview of the genus Colletotrichum, the species complexes described so far and the most common lifestyles in the genus, with a special emphasis on the mechanisms that may be responsible, at least in part, for the emergence of new genotypes under field conditions.
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Affiliation(s)
- Leandro Lopes da Silva
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Hanna Lorena Alvarado Moreno
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Hilberty Lucas Nunes Correia
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Mateus Ferreira Santana
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Marisa Vieira de Queiroz
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil.
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Chen ECH, Mathieu S, Hoffrichter A, Sedzielewska-Toro K, Peart M, Pelin A, Ndikumana S, Ropars J, Dreissig S, Fuchs J, Brachmann A, Corradi N. Single nucleus sequencing reveals evidence of inter-nucleus recombination in arbuscular mycorrhizal fungi. eLife 2018; 7:e39813. [PMID: 30516133 PMCID: PMC6281316 DOI: 10.7554/elife.39813] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/16/2018] [Indexed: 12/18/2022] Open
Abstract
Eukaryotes thought to have evolved clonally for millions of years are referred to as ancient asexuals. The oldest group among these are the arbuscular mycorrhizal fungi (AMF), which are plant symbionts harboring hundreds of nuclei within one continuous cytoplasm. Some AMF strains (dikaryons) harbor two co-existing nucleotypes but there is no direct evidence that such nuclei recombine in this life-stage, as is expected for sexual fungi. Here, we show that AMF nuclei with distinct genotypes can undergo recombination. Inter-nuclear genetic exchange varies in frequency among strains, and despite recombination all nuclear genomes have an average similarity of at least 99.8%. The present study demonstrates that AMF can generate genetic diversity via meiotic-like processes in the absence of observable mating. The AMF dikaryotic life-stage is a primary source of nuclear variability in these organisms, highlighting its potential for strain enhancement of these symbionts.
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Affiliation(s)
- Eric CH Chen
- Department of BiologyUniversity of OttawaOttawaCanada
| | | | - Anne Hoffrichter
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
| | - Kinga Sedzielewska-Toro
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
| | - Max Peart
- Department of BiologyUniversity of OttawaOttawaCanada
| | - Adrian Pelin
- Department of BiologyUniversity of OttawaOttawaCanada
| | | | - Jeanne Ropars
- Department of BiologyUniversity of OttawaOttawaCanada
| | - Steven Dreissig
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGaterslebenGermany
| | - Jorg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGaterslebenGermany
| | - Andreas Brachmann
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
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Mehrabi R, Mirzadi Gohari A, Kema GHJ. Karyotype Variability in Plant-Pathogenic Fungi. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:483-503. [PMID: 28777924 DOI: 10.1146/annurev-phyto-080615-095928] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Recent advances in genetic and molecular technologies gradually paved the way for the transition from traditional fungal karyotyping to more comprehensive chromosome biology studies. Extensive chromosomal polymorphisms largely resulting from chromosomal rearrangements (CRs) are widely documented in fungal genomes. These extraordinary CRs in fungi generate substantial genome plasticity compared to other eukaryotic organisms. Here, we review the most recent findings on fungal CRs and their underlying mechanisms and discuss the functional consequences of CRs for adaptation, fungal evolution, host range, and pathogenicity of fungal plant pathogens in the context of chromosome biology. In addition to a complement of permanent chromosomes called core chromosomes, the genomes of many fungal pathogens comprise distinct unstable chromosomes called dispensable chromosomes (DCs) that also contribute to chromosome polymorphisms. Compared to the core chromosomes, the structural features of DCs usually differ for gene density, GC content, housekeeping genes, and recombination frequency. Despite their dispensability for normal growth and development, DCs have important biological roles with respect to pathogenicity in some fungi but not in others. Therefore, their evolutionary origin is also reviewed in relation to overall fungal physiology and pathogenicity.
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Affiliation(s)
- Rahim Mehrabi
- Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
- Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
| | - Amir Mirzadi Gohari
- Department of Plant Pathology, Faculty of Agricultural Sciences and Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
- Wageningen Plant Research, Wageningen University and Research, 6700AA Wageningen, The Netherlands;
| | - Gert H J Kema
- Wageningen Plant Research, Wageningen University and Research, 6700AA Wageningen, The Netherlands;
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Beirn LA, Clarke BB, Crouch JA. Influence of host and geographic locale on the distribution of Colletotrichum cereale lineages. PLoS One 2014; 9:e97706. [PMID: 24842654 PMCID: PMC4026525 DOI: 10.1371/journal.pone.0097706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/22/2014] [Indexed: 01/09/2023] Open
Abstract
Colletotrichum cereale is an ascomycete inhabitant of cool-season Pooideae grasses. The fungus has increased in frequency over the past decade as a destructive pathogen of Poa annua and Agrostis stolonifera turfgrass. Colletotrichum cereale exists as two lineages, designated clades A and B, but little is known about the distribution of these clades in natural environments, or what role these subdivisions may play in the trajectory of disease outbreaks. In this study, our objective was to determine the frequency of C. cereale clades A and B. To rapidly discriminate between the two C. cereale clades, a real-time PCR assay was developed based on the Apn2 gene. A collection of 700 C. cereale pathogens and endophytes from twenty Pooideae grass genera were genotyped. 87% of the collection was identifed as part of clade A, 11.7% as part of clade B, and 1.3% was a mixture. Colletotrichum cereale from turfgrass hosts in North America were most commonly members of clade A (78%). The overabundance of clade A in turfgrass isolates was directly attributable to the dominance of this lineage from southern sampling sites, irrespective of host. In contrast, 111 C. cereale turfgrass isolates collected from northern sampling sites were evenly distributed between clades A and B. Only 28% of C. cereale from A. stolonifera at northern sampling sites were part of clade A. These data show that environmental factors such as geographic location and host identity likely played a role in the distribution of the major C. cereale clades in North American turfgrass.
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Affiliation(s)
- Lisa A. Beirn
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Bruce B. Clarke
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Jo Anne Crouch
- Systematic Mycology and Microbiology Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Beltsville, Maryland, United States of America
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Rosada LJ, Sant'anna JR, Franco CCS, Esquissato GNM, Santos PASR, Yajima JPRS, Ferreira FD, Machinski M, Corrêa B, Castro-Prado MAA. Identification of Aspergillus flavus isolates as potential biocontrol agents of aflatoxin contamination in crops. J Food Prot 2013; 76:1051-5. [PMID: 23726204 DOI: 10.4315/0362-028x.jfp-12-436] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.
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Affiliation(s)
- L J Rosada
- Departamento de Biotecnologia, Genética e Biologia Celular, Laboratório de Genética de Microrganismos, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, CEP 87020-900, PR, Brasil
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11
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da Silva Franco CC, de Sant' Anna JR, Rosada LJ, Kaneshima EN, Stangarlin JR, De Castro-Prado MAA. Vegetative compatibility groups and parasexual segregation in Colletotrichum acutatum isolates infecting different hosts. PHYTOPATHOLOGY 2011; 101:923-928. [PMID: 21425929 DOI: 10.1094/phyto-12-10-0327] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Heterokaryosis is an important mechanism which provides genetic variability increase in filamentous fungi. In order to assess the diversity of vegetative compatibility reactions existing among Colletotrichum acutatum isolates derived from different hosts, complementary nit mutants of each isolate were obtained and paired in all possible combinations. Vegetative compatibility groups (VCG) were identified among the isolates according to their ability to form viable heterokaryons. Seven VCGs were identified among the isolates, one of which contained isolates from different hosts. VCGs 2 and 6 contained two and three members, respectively; VCG-3 contained four members, and four VCGs (1, 4, 5, and 7) contained a single one. This study shows, for the first time, the isolation and the parasexual segregation of a heterozygous diploid sector derived from the heterokaryon formed with nit mutants from VCG-6. Diploid, named DE-3, showed nit+ phenotype and growth rate similar to the parental wild isolate. When inoculated in the presence of the haploidizing agent benomyl, the diploid strain produced parasexual haploid segregants exhibiting the nit phenotypes of the crossed mutants. Since viable heterokaryons and diploid may be formed among vegetative compatible isolates of C. acutatum, this study suggests that the parasexual cycle may be an alternative source of genetic variability in C. acutatum isolates.
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