1
|
Moura-Mendes J, Cazal-Martínez CC, Rojas C, Ferreira F, Pérez-Estigarribia P, Dias N, Godoy P, Costa J, Santos C, Arrua A. Species Identification and Mycotoxigenic Potential of Aspergillus Section Flavi Isolated from Maize Marketed in the Metropolitan Region of Asunción, Paraguay. Microorganisms 2023; 11:1879. [PMID: 37630439 PMCID: PMC10458825 DOI: 10.3390/microorganisms11081879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/13/2023] [Accepted: 07/18/2023] [Indexed: 08/27/2023] Open
Abstract
Zea mays var. amylacea and Zea mays var. indurata are maize ecotypes from Paraguay. Aspergillus section Flavi is the main spoilage fungus of maize under storage conditions. Due to its large intraspecific genetic variability, the accurate identification of this fungal taxonomic group is difficult. In the present study, potential mycotoxigenic strains of Aspergillus section Flavi isolated from Z. mays var. indurata and Z. mays var. amylacea that are marketed in the metropolitan region of Asunción were identified by a polyphasic approach. Based on morphological characters, 211 isolates were confirmed to belong to Aspergillus section Flavi. A subset of 92 strains was identified as Aspergillus flavus by mass spectrometry MALDI-TOF and the strains were classified by MALDI-TOF MS into chemotypes based on their aflatoxins and cyclopiazonic acid production. According to the partial sequencing of ITS and CaM genes, a representative subset of 38 A. flavus strains was confirmed. Overall, 75 A. flavus strains (86%) were characterized as producers of aflatoxins. The co-occurrence of at least two mycotoxins (AF/ZEA, FUM/ZEA, and AF/ZEA/FUM) was detected for five of the Z. mays samples (63%). Considering the high mycological bioburden and mycotoxin contamination, maize marketed in the metropolitan region of Asunción constitutes a potential risk to food safety and public health and requires control measures.
Collapse
Affiliation(s)
- Juliana Moura-Mendes
- Centro Multidisciplinario de Investigaciones Tecnológicas, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay; (J.M.-M.)
| | - Cinthia C. Cazal-Martínez
- Centro Multidisciplinario de Investigaciones Tecnológicas, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay; (J.M.-M.)
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay
| | - Cinthia Rojas
- Centro Multidisciplinario de Investigaciones Tecnológicas, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay; (J.M.-M.)
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay
| | - Francisco Ferreira
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay
| | - Pastor Pérez-Estigarribia
- Facultad Politécnica, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay
- Facultad de Medicina, Universidad Sudamericana, Pedro Juan Caballero 130112, Paraguay
| | - Nathalia Dias
- BIOREN-UFRO Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile
| | - Patrício Godoy
- Instituto de Microbiología Clínica, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5090000, Chile
| | - Jéssica Costa
- Departamento de Biologia, Instituto de Ciências Biológicas-ICB, Universidade Federal do Amazonas, Av. Rodrigo Otávio Jordão Ramos 3000, Bloco 01, Manaus 69077-000, Brazil;
| | - Cledir Santos
- Department of Chemical Science and Natural Resources, Universidad de La Frontera, Temuco 4811230, Chile
| | - Andrea Arrua
- Centro Multidisciplinario de Investigaciones Tecnológicas, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay; (J.M.-M.)
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Asunción, San Lorenzo 111421, Paraguay
| |
Collapse
|
2
|
Zhang W, Chang X, Wu Z, Dou J, Yin Y, Sun C, Wu W. Rapid isolation of non-aflatoxigenic Aspergillus flavus strains. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2019.2490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In the present study, a method for screening non-aflatoxigenic Aspergillus flavus in soil samples collected from major peanut-growing regions of China was developed. The single colonies were picked and cultured on Aspergillus flavus and parasiticus agar (AFPA). If the reverse side of the colony on AFPA was orange-coloured, it was considered A. flavus or Aspergillus parasiticus. After the genomic DNA of each strain was extracted, 28S rRNA and calmodulin were amplified and sequenced to determine the species. The key gene, aflR, was amplified and digested via polymerase chain reaction-restriction fragment length polymorphism. The aflatoxigenic A. flavus and the non-aflatoxigenic A. flavus and A. parasiticus were distinguished by enzyme digestion of aflR. 156 strains of A. flavus were screened, which consisted of 135 aflatoxigenic and 21 non-aflatoxigenic strains. The aflatoxin producing ability of each strain was confirmed using solid-state fermentation experiments. Using the method developed in the present study, we confirmed that the non-aflatoxigenic A. flavus strains isolated lost their capacity to produce aflatoxins. Considering there could be some alterations in other functional genes, some non-aflatoxigenic strains could be identified inaccurately as aflatoxigenic strains, although that did not occur in the present study. The growth of non-aflatoxigenic A. flavus was observed, and the most rapidly growing non-aflatoxigenic strain was selected for plate confrontation assays and toxic mixed culture experiments. The inhibition rate of non-aflatoxigenic A. flavus against aflatoxigenic A. flavus was 55.4 and 72.6% in potato dextrose agar (PDA) plate and natural soybean medium, respectively. The screened non-aflatoxigenic A. flavus strains provide a microbial resource for biological control of aflatoxin contamination.
Collapse
Affiliation(s)
- W. Zhang
- Department of Biological and Agricultural Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130022, China P.R
- Academy of National Food and Strategic Reserves Administration P.R.C, No.11 Baiwanzhuang Avenue, Xicheng District, Beijing 100037, China P.R
| | - X. Chang
- Academy of National Food and Strategic Reserves Administration P.R.C, No.11 Baiwanzhuang Avenue, Xicheng District, Beijing 100037, China P.R
| | - Z. Wu
- Department of Biological and Agricultural Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130022, China P.R
| | - J. Dou
- Department of Biological and Agricultural Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130022, China P.R
| | - Y. Yin
- Academy of National Food and Strategic Reserves Administration P.R.C, No.11 Baiwanzhuang Avenue, Xicheng District, Beijing 100037, China P.R
| | - C. Sun
- Academy of National Food and Strategic Reserves Administration P.R.C, No.11 Baiwanzhuang Avenue, Xicheng District, Beijing 100037, China P.R
| | - W. Wu
- Department of Biological and Agricultural Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130022, China P.R
| |
Collapse
|
3
|
Drott MT, Fessler LM, Milgroom MG. Population Subdivision and the Frequency of Aflatoxigenic Isolates in Aspergillus flavus in the United States. PHYTOPATHOLOGY 2019; 109:878-886. [PMID: 30480472 DOI: 10.1094/phyto-07-18-0263-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Consumption of food contaminated with aflatoxin, from crops infected by Aspergillus flavus, is associated with acute toxicosis, cancer, and stunted growth. Although such contamination is more common in the lower latitudes of the United States, it is unclear whether this pattern is associated with differences in the relative frequencies of aflatoxigenic individuals of A. flavus. To determine whether the frequency of the aflatoxin-producing ability of A. flavus increases as latitude decreases, we sampled 281 isolates from field soils in two north-south transects in the United States and tested them for aflatoxin production. We also genotyped 161 isolates using 10 microsatellite markers to assess population structure. Although the population density of A. flavus was highest at lower latitudes, there was no difference in the frequency of aflatoxigenic A. flavus isolates in relation to latitude. We found that the U.S. population of A. flavus is subdivided into two genetically differentiated subpopulations that are not associated with the chemotype or geographic origin of the isolates. The two populations differ markedly in allelic and genotypic diversity. The less diverse population is more abundant and may represent a clonal lineage derived from the more diverse population. Overall, increased aflatoxin contamination in lower latitudes may be explained partially by differences in the population density of A. flavus, not genetic population structure.
Collapse
Affiliation(s)
- Milton T Drott
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| | - Lauren M Fessler
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| | - Michael G Milgroom
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| |
Collapse
|
4
|
Singh D, Radhakrishnan T, Kumar V, Bagwan NB, Basu MS, Dobaria JR, Mishra GP, Chanda SV. Molecular characterisation of Aspergillus flavus isolates from peanut fields in India using AFLP. Braz J Microbiol 2015; 46:673-82. [PMID: 26413047 PMCID: PMC4568877 DOI: 10.1590/s1517-838246320131115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Accepted: 11/12/2014] [Indexed: 11/22/2022] Open
Abstract
Aflatoxin contamination of peanut, due to infection by Aspergillus flavus, is a major problem of rain-fed agriculture in India. In the present study, molecular characterisation of 187 Aspergillus flavus isolates, which were sampled from the peanut fields of Gujarat state in India, was performed using AFLP markers. On a pooled cluster analysis, the markers could successfully discriminate among the 'A', 'B' and 'G' group A. flavus isolates. PCoA analysis also showed equivalent results to the cluster analysis. Most of the isolates from one district could be clustered together, which indicated genetic similarity among the isolates. Further, a lot of genetic variability was observed within a district and within a group. The results of AMOVA test revealed that the variance within a population (84%) was more than that between two populations (16%). The isolates, when tested by indirect competitive ELISA, showed about 68.5% of them to be atoxigenic. Composite analysis between the aflatoxin production and AFLP data was found to be ineffective in separating the isolate types by aflatoxigenicity. Certain unique fragments, with respect to individual isolates, were also identified that may be used for development of SCAR marker to aid in rapid and precise identification of isolates.
Collapse
Affiliation(s)
| | | | - Vinod Kumar
- Directorate of Groundnut Research, Gujarat, India
| | - N B Bagwan
- Directorate of Groundnut Research, Gujarat, India
| | - M S Basu
- Directorate of Groundnut Research, Gujarat, India
| | - J R Dobaria
- Directorate of Groundnut Research, Gujarat, India
| | | | - S V Chanda
- Department of Biosciences, Saurashtra University, Gujarat, India
| |
Collapse
|
5
|
Chulze S, Palazzini J, Torres AM, Barros G, Ponsone M, Geisen R, Schmidt-Heydt M, Köhl J. Biological control as a strategy to reduce the impact of mycotoxins in peanuts, grapes and cereals in Argentina. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2014; 32:471-9. [DOI: 10.1080/19440049.2014.984245] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
6
|
Massi FP, Vieira MLC, Sartori D, Penha RES, de Freitas Munhoz C, Ferreira JM, Iamanaka BT, Taniwaki MH, Frisvad JC, Fungaro MHP. Brazil nuts are subject to infection with B and G aflatoxin-producing fungus, Aspergillus pseudonomius. Int J Food Microbiol 2014; 186:14-21. [PMID: 24974275 DOI: 10.1016/j.ijfoodmicro.2014.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/15/2014] [Accepted: 06/09/2014] [Indexed: 11/19/2022]
Abstract
The exploitation of the Brazil nut is one of the most important activities of the extractive communities of the Amazon rainforest. However, its commercialization can be affected by the presence of aflatoxins produced by fungi, namely Aspergillus section Flavi. In the present study, we investigated a collection of Aspergillus nomius strains isolated from Brazil nuts using different approaches, including morphological characters, RAPD and AFLP profiles, partial β-tubulin and calmodulin nucleotide sequences, aflatoxin patterns, as well as tolerance to low water activity in cultured media. Results showed that most of the isolates do belong to A. nomius species, but a few were re-identified as Aspergillus pseudonomius, a very recently described species. The results of the analyses of molecular variance, as well as the high pairwise FST values between A. nomius and A. pseudonomius suggested the isolation between these two species and the inexistence of gene flow. Fixed interspecific nucleotide polymorphisms at β-tubulin and calmodulin loci are presented. All A. pseudonomius strains analyzed produced aflatoxins AFB1, AFB2, AFG1 and AFG2. This study contains the first-ever report on the occurrence in Brazil nuts of A. pseudonomius. The G-type aflatoxins and the mycotoxin tenuazonic acid are reported here for the first time in A. pseudonomius.
Collapse
Affiliation(s)
- Fernanda Pelisson Massi
- Centro de Ciências Biológicas, Universidade Estadual de Londrina, P.O. Box 6001, Londrina 86051-990, Brazil.
| | - Maria Lúcia Carneiro Vieira
- Departamento de Genética, Escola Superior de Agricultura "Luiz de Queiroz" USP, P.O. Box 83, Piracicaba 13400-970, Brazil.
| | - Daniele Sartori
- Centro de Ciências Biológicas, Universidade Estadual de Londrina, P.O. Box 6001, Londrina 86051-990, Brazil.
| | - Rafael Elias Silva Penha
- Centro de Ciências Biológicas, Universidade Estadual de Londrina, P.O. Box 6001, Londrina 86051-990, Brazil.
| | - Carla de Freitas Munhoz
- Departamento de Genética, Escola Superior de Agricultura "Luiz de Queiroz" USP, P.O. Box 83, Piracicaba 13400-970, Brazil.
| | - Josué Maldonado Ferreira
- Centro de Ciências Biológicas, Universidade Estadual de Londrina, P.O. Box 6001, Londrina 86051-990, Brazil.
| | | | | | - Jens C Frisvad
- Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark.
| | | |
Collapse
|
7
|
Molecular characterization of atoxigenic Aspergillus flavus isolates collected in China. J Microbiol 2014; 52:559-65. [DOI: 10.1007/s12275-014-3629-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/18/2014] [Accepted: 02/24/2014] [Indexed: 10/25/2022]
|
8
|
Zhang CS, Xing FG, Selvaraj JN, Yang QL, Zhou L, Zhao YJ, Liu Y. The effectiveness of ISSR profiling for studying genetic diversity of Aspergillus flavus from peanut-cropped soils in China. BIOCHEM SYST ECOL 2013. [DOI: 10.1016/j.bse.2013.03.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
9
|
Alaniz Zanon M, Chiotta M, Giaj-Merlera G, Barros G, Chulze S. Evaluation of potential biocontrol agent for aflatoxin in Argentinean peanuts. Int J Food Microbiol 2013; 162:220-5. [DOI: 10.1016/j.ijfoodmicro.2013.01.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 01/08/2013] [Accepted: 01/12/2013] [Indexed: 11/15/2022]
|
10
|
Mehl HL, Jaime R, Callicott KA, Probst C, Garber NP, Ortega-Beltran A, Grubisha LC, Cotty PJ. Aspergillus flavusdiversity on crops and in the environment can be exploited to reduce aflatoxin exposure and improve health. Ann N Y Acad Sci 2012; 1273:7-17. [DOI: 10.1111/j.1749-6632.2012.06800.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
11
|
Reis GM, Rocha LDO, Atayde DD, Batatinha MM, Corrêa B. Molecular characterization by amplified fragment length polymorphism and aflatoxin production of Aspergillus flavus isolated from freshly harvested peanut in Brazil. WORLD MYCOTOXIN J 2012. [DOI: 10.3920/wmj2011.1350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brazil contributes substantially to the global peanut production, and the state of São Paulo is the largest producer in the country. Peanut crops can be contaminated by Aspergillus flavus strains producing aflatoxins, which are highly toxic and carcinogenic. Thus, the production of high-quality peanuts is crucial both for the commercial peanut industry and as a matter of public health. In this study, we used amplified fragment length polymorphism analysis (AFLP) to investigate the genetic variability among A. flavus strains isolated from fresh peanuts harvested in four different regions in the state of São Paulo, and to determine whether the molecular genetic profiles correlated with aflatoxin production or sclerotia formation. AFLP analysis generated 78 fragments ranging from 27 to 365 base pairs in length. Thirteen percent were not polymorphic. Genotyping identified twelve groups of A. flavus. On the basis of the polymorphisms identified, similarity between the isolates ranged from 37% to 100%. Of all isolates collected, 91.7% produced aflatoxins and 83.9% produced small sclerotia. Statistical analysis failed to suggest any relationship between the presence of sclerotia and mean levels of aflatoxins B1 and B2. Furthermore, a dendrogram based on AFLP data revealed substantial genetic variability among the A. flavus strains, but showed no correlation between dendrogram groups separated by molecular genetic features and production of aflatoxins B1 or B2 or the formation of sclerotia.
Collapse
Affiliation(s)
- G. Martins Reis
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Av. Prof. Lineu Prestes 1374, lab. 249, Cidade Universitária, 05508-000 São Paulo, Brazil
| | - L. de Oliveira Rocha
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Av. Prof. Lineu Prestes 1374, lab. 249, Cidade Universitária, 05508-000 São Paulo, Brazil
| | - D. Diniz Atayde
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Av. Prof. Lineu Prestes 1374, lab. 249, Cidade Universitária, 05508-000 São Paulo, Brazil
| | - M.J. Moreira Batatinha
- Department of Pathology, School of Veterinary Medicine, Federal University of Bahia, Salvador, Av. Ademar de Barros, n. 500, 40110-170 Ondina, Ba, Brazil
| | - B. Corrêa
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Av. Prof. Lineu Prestes 1374, lab. 249, Cidade Universitária, 05508-000 São Paulo, Brazil
| |
Collapse
|
12
|
Characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates from pistachio. Mycotoxin Res 2011; 28:67-75. [DOI: 10.1007/s12550-011-0117-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 10/27/2011] [Accepted: 11/01/2011] [Indexed: 10/15/2022]
|
13
|
Chiotta M, Reynoso M, Torres A, Combina M, Chulze S. Molecular characterization and toxigenic profile of Aspergillus section Nigri populations isolated from the main grape-growing regions in Argentina. J Appl Microbiol 2010; 110:445-54. [DOI: 10.1111/j.1365-2672.2010.04898.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
14
|
Cárdenas-Flores A, Draye X, Bivort C, Cranenbrouck S, Declerck S. Impact of multispores in vitro subcultivation of Glomus sp. MUCL 43194 (DAOM 197198) on vegetative compatibility and genetic diversity detected by AFLP. MYCORRHIZA 2010; 20:415-425. [PMID: 20082102 DOI: 10.1007/s00572-009-0295-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Accepted: 12/14/2009] [Indexed: 05/28/2023]
Abstract
Vegetative compatibility and amplified fragment length polymorphism (AFLP) genotyping of in vitro multispores clonal lineages, issued from the same ancestor culture of the arbuscular mycorrhizal fungal strain MUCL 43194 and subcultured several generations in different locations, was assessed. Vegetative compatibility was studied by confronting the germ tubes of two spores from the same or different clonal lineages and stained with nitrotetrazolium blue-Trypan blue and diamidinophenylindole to detect hyphal fusions and nuclei, respectively. Further AFLP analysis of single spores was performed to assess the genetic profile and Dice similarity between clonal lineages. Germ tubes of spores distant by as many as 69 generations were capable of fusing. The anastomosis frequencies averaged 69% between spores from the same clonal lineage, 57% between spores from different clonal lineages, and 0% between spores belonging to different strains. The AFLP patterns showed similarities averaging 92% within clonal lineages and 86% between clonal lineages. Each spore presented unique genotype and some of them shared more markers with spores from different lineages than within the same lineage. We showed that MUCL 43194 maintained self-recognition for long periods of subcultures in vitro and that spores involved in compatibility tests had different genotypes. Our findings suggest that MUCL 43194 maintains genetic diversity by means of anastomoses.
Collapse
|
15
|
Grubisha LC, Cotty PJ. Genetic isolation among sympatric vegetative compatibility groups of the aflatoxin-producing fungus Aspergillus flavus. Mol Ecol 2009; 19:269-80. [PMID: 20025654 DOI: 10.1111/j.1365-294x.2009.04467.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Aspergillus flavus, a fungal pathogen of animals and both wild and economically important plants, is most recognized for producing aflatoxin, a cancer-causing secondary metabolite that contaminates food and animal feed globally. Aspergillus flavus has two self/nonself recognition systems, a sexual compatibility system and a vegetative incompatibility system, and both play a role in directing gene flow in populations. Aspergillus flavus reproduces clonally in wild and agricultural settings, but whether a cryptic sexual stage exists in nature is currently unknown. We investigated the distribution of genetic variation in 243 samples collected over 4 years from three common vegetative compatibility groups (VCGs) in Arizona and Texas from cotton using 24 microsatellite loci and the mating type locus (MAT) to assess population structure and potential gene flow among A. flavus VCGs in sympatric populations. All isolates within a VCG had the same mating type with OD02 having MAT1-2 and both CG136 and MR17 having MAT1-1. Our results support the hypothesis that these three A. flavus VCGs are genetically isolated. We found high levels of genetic differentiation and no evidence of gene flow between VCGs, including VCGs of opposite mating-type. Our results suggest that these VCGs diverged before domestication of agricultural hosts (>10,000 yr bp).
Collapse
Affiliation(s)
- L C Grubisha
- United States Department of Agriculture, Agriculture Research Service, School of Plant Sciences, The University of Arizona, PO Box 210036, Tucson, AZ 85721-0036, USA
| | | |
Collapse
|
16
|
Abstract
Aspergillus flavus is the major producer of carcinogenic aflatoxins in crops worldwide and is also an important opportunistic human pathogen in aspergillosis. The sexual state of this heterothallic fungus is described from crosses between strains of the opposite mating type. Sexual reproduction occurred between sexually compatible strains belonging to different vegetative compatibility groups. Multiple, indehiscent ascocarps containing asci and ascospores formed within the pseudoparenchymatous matrix of stromata, which places the fungus in genus Petromyces. The teleomorph of P. flavus could not be distinguished from that of P. parasiticus (anamorph = A. parasiticus), another aflatoxin-producing species, based on morphology of the sexual structures. The two species can be separated by anamorph morphology, mycotoxin profile and molecular characters.
Collapse
Affiliation(s)
- Bruce W Horn
- National Peanut Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Dawson, Georgia 39842, USA.
| | | | | |
Collapse
|
17
|
Yin Y, Lou T, Yan L, Michailides TJ, Ma Z. Molecular characterization of toxigenic and atoxigenic Aspergillus flavus isolates, collected from peanut fields in China. J Appl Microbiol 2009; 107:1857-65. [PMID: 19457031 DOI: 10.1111/j.1365-2672.2009.04356.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The objectives of this study were to assess the genetic relationships between toxigenic and atoxigenic isolates of Aspergillus flavus collected from peanut fields in China, and to analyse deletions within the aflatoxin biosynthetic gene cluster for the atoxigenic isolates. METHODS AND RESULTS Analysis of random-amplified polymorphic DNA and microsatellite-primed PCR data showed that the toxigenic and atoxigenic isolates of A. flavus were not clustered based on their regions and their ability of aflatoxin and sclerotial production. These results were further supported by DNA sequence of ITS, pksA and omtA genes. PCR assays showed that 24 of 35 isolates containing no detectable aflatoxins had the entire aflatoxin gene cluster. Eleven atoxigenic isolates had five different deletion patterns in the cluster. CONCLUSIONS Toxigenic and atoxigenic isolates of A. flavus are genetically similar, but some atoxigenic isolates having deletions within the aflatoxin gene cluster can be identified readily by PCR assays. SIGNIFICANCE AND IMPACT OF THE STUDY Because the extensive deletions within the aflatoxin gene cluster are not rare in the atoxigenic isolates, analysis of deletion within the cluster would be an effective method for the rapid screening of atoxigenic isolates for developing biocontrol agents.
Collapse
Affiliation(s)
- Y Yin
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Ministry of Agriculture, Zhejiang University, Hangzhou, China
| | | | | | | | | |
Collapse
|
18
|
Horn BW, Ramirez-Prado JH, Carbone I. The sexual state of Aspergillus parasiticus. Mycologia 2009; 101:275-80. [PMID: 19397202 DOI: 10.3852/08-205] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The sexual state of Aspergillus parasiticus, a potent aflatoxin-producing fungus within section Flavi, is described. The production of nonostiolate ascocarps surrounded by a separate peridium within the stroma places the teleomorph in genus Petromyces. Petromyces parasiticus differs from P. alliaceus by its larger ascospores with finely tuberculate ornamentation. The anamorphic Aspergillus states of the two species differ in conidial head color and microscopic characters.
Collapse
Affiliation(s)
- Bruce W Horn
- National Peanut Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Dawson, Georgia 39842, USA.
| | | | | |
Collapse
|
19
|
Martínez-Culebras PV, Crespo-Sempere A, Sánchez-Hervás M, Elizaquivel P, Aznar R, Ramón D. Molecular characterization of the black Aspergillus isolates responsible for ochratoxin A contamination in grapes and wine in relation to taxonomy of Aspergillus section Nigri. Int J Food Microbiol 2009; 132:33-41. [PMID: 19401261 DOI: 10.1016/j.ijfoodmicro.2009.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 02/09/2009] [Accepted: 03/20/2009] [Indexed: 11/27/2022]
Abstract
This work examines ochratoxigenic mycobiota in grapes by ap-PCR analysis sequence analysis of the ITS and IGS regions and ability to produce OTA. A comparison was also made with many reference strains of Aspergillus section Nigri. Based on ap-PCR profiles, derived from two microsatellite primers, three main groups were obtained by UPGMA cluster analysis corresponding to A. carbonarius, A. niger and A. tubingensis. The cophenetic correlation values corresponding to ap-PCR UPGMA analysis revealed a higher genetic variability in A. niger and A. tubingensis than in A. carbonarius. In addition, no genotypical differences could be established between OTA producers and nonproducers in all species analysed. Phylogenetic relationships inferred from ITS and IGS sequences are, mostly, congruent with earlier works. A. niger and A. tubingensis strains were closely related, but not identical, and they clustered into two distinct groups within the A. niger aggregate. Sequence analysis also showed genetic divergences between strains of A. foetidus and the rest of the Aspergillus section Nigri. Additionally, the phylogenetic analysis was consistent in separating a new group of ochratoxigenic strains, frequently isolated from grapes, named A. tubingensis-like. All strains of A. carbonarius analysed by sequence analysis had identical ITS and IGS sequences confirming the lack of significant genetic variability within this important ochratoxigenic species.
Collapse
Affiliation(s)
- P V Martínez-Culebras
- Departamento de Medicina Preventiva y Salud Pública, Ciencias de la Alimentación, Bromatología, Toxicología y Medicina Legal, Universitat de València, Vicente Andrès Estellès s/n, Burjassot, Valencia, Spain.
| | | | | | | | | | | |
Collapse
|