scholarly journals Reassessment of Vegetative Compatibility of Sclerotinia homoeocarpa Using Nitrate-Nonutilizing Mutants

2008 ◽  
Vol 98 (1) ◽  
pp. 108-114 ◽  
Author(s):  
Y.-K. Jo ◽  
S. W. Chang ◽  
J. Rees ◽  
G. Jung
Keyword(s):  
Minimal Medium ◽  
The United States ◽  
Vegetative Compatibility ◽  
Complete Medium ◽  
Sclerotinia Homoeocarpa ◽  
Hyphal Fusion ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Mutant Phenotypes ◽  
First Time

Nitrate-nonutilizing (nit) mutants were recovered for the first time from 21 isolates of Sclerotinia homoeocarpa collected in the United States. Mutants were selected from shredded mycelium of each isolate when cultured on water agar medium amended with 4% (wt/vol) potassium chlorate. The mutants could be classified into three phenotypes: nit1, nit3, and NitM, based on their growth on minimal medium (Czapek solution agar) supplemented with NaNO2 or hypoxanthine. Complementary heterokaryons were observed in pairings between different phenotypes of nit mutants derived from compatible isolates, but not in self-fusions or pairings between incompatible isolates. The vigor of prototrophic growth varied with isolates and mutant phenotypes. Strong and continuous heterokaryons, as well as weak and spontaneous ones, formed depending on pairings of nit mutants. Stable heterokaryons between compatible isolates, but apoptotic reactions between incompatible isolates, were observed immediately after hyphal fusion under the epifluorescence microscope. The 21 isolates used in this study, which were previously assigned into 11 different vegetative compatibility groups (VCGs) based on the formation of a barrage zone at the contact site of paired isolates on complete medium (potato dextrose agar), were regrouped into five VCGs based on heterokaryon formation between nit mutants on minimal medium.

Vegetative compatibility within Fusarium oxysporum f.sp. niveum and its relationship to virulence, aggressiveness, and race

1990 ◽  
Vol 36 (5) ◽  
pp. 352-358 ◽  
Author(s):  
R. P. Larkin ◽  
D. L. Hopkins ◽  
F. N. Martin
Keyword(s):  
Fusarium Oxysporum ◽  
The United States ◽  
Soil Samples ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
The World ◽  
Infested Field ◽  
Race 1 ◽  
Race 2

Over 250 isolates of Fusarium oxysporum collected from infected watermelon plants and soil samples from a pathogen-infested field, as well as known isolates of F. oxysporum f. sp. niveum imported from various locations around the world, were tested for pathogenicity on watermelon and used to determine vegetative compatibility groups (VCGs) within F. oxysporum f. sp. niveum. Vegetative compatibility was assessed on the basis of heterokaryon formation among nitrate-nonutilizing mutants. Race determinations were made by screening isolates on six different watermelon cultivars of varying resistance. All isolates of F. oxysporum f. sp. niveum belonged to one of three distinct VCGs, and were incompatible with isolates that were not pathogenic on watermelon. Isolates of F. oxysporum f. sp. niveum were subdivided into two races and there was a direct relationship between VCG and race. VCG 0080 consisted of race 1 isolates from five states of the United States, Taiwan, and Australia. VCG 0081 consisted solely of race 1 isolates from Florida. VCG 0082 was comprised solely of race 2 isolates, all of which were capable of causing severe wilt on all cultivars tested. Numerous Florida isolates were compatible with race 2 isolates from Texas and demonstrated comparable virulence on all cultivars, confirming the presence of race 2 in Florida. With F. oxysporum f. sp. niveum, vegetative compatibility can be utilized as an alternative or collaborative method to distinguish pathogenic from nonpathogenic strains of F. oxysporum and to differentiate subforma specialis virulence characteristics. Key words: fusarium wilt, nit mutants, watermelon.

scholarly journals Sexual Recombination in Gibberella zeae

1999 ◽  
Vol 89 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Robert L. Bowden ◽  
John F. Leslie
Keyword(s):  
The United States ◽  
Vegetative Compatibility ◽  
Gibberella Zeae ◽  
Rapid Testing ◽  
Wild Type ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Sexual Recombination ◽  
Group 2 ◽  
Group 1

We developed a method for inducing sexual outcrosses in the homothallic Ascomycete fungus Gibberella zeae (anamorph: Fusarium graminearum). Strains were marked with different nitrate nonutilizing (nit) mutations, and vegetative compatibility groups served as additional markers in some crosses. Strains with complementary nit mutations were cocultured on carrot agar plates. Ascospores from individual perithecia were plated on a minimal medium (MM) containing nitrate as the sole nitrogen source. Crosses between different nit mutants segregated in expected ratios (3:1 nit-:nit+) from heterozygous perithecia. Analysis of vegetative compatibility groups of progeny of two crosses indicated two and three vegetative incompatibility (vic) genes segregating, respectively. For rapid testing of sexual recombination between nit mutants, perithecia were inverted over MM to deposit actively discharged ascospores. Development of proto-trophic wild-type colonies was taken as evidence of sexual recombination. Strains of G. zeae group 2 from Japan, Nepal, and South Africa, and from Indiana, Kansas, and Ohio in the United States were sexually interfertile. Four group 1 strains were not interfertile among themselves or with seven group 2 strains. Attempts to cross G. zeae with representatives of F. acuminatum, F. avenaceum, F. culmorum, F. crookwellense, F. oxysporum, and three mating populations of G. fujikuroi were not successful.

scholarly journals Genetic variability and vegetative compatibility in Aspergillus niger isolated from various food substances in Benin City Nigeria

2021 ◽  
Vol 24 (12) ◽  
pp. 2161-2165
Author(s):  
L. Eboigbe ◽  
M.O. Omoregbe
Keyword(s):  
Aspergillus Niger ◽  
Minimal Medium ◽  
Genetic Recombination ◽  
Potato Dextrose Agar ◽  
Vegetative Compatibility ◽  
Complementation Test ◽  
Vegetative Compatibility Groups ◽  
Benin City ◽  
Nit Mutants ◽  
Mutant Strains

In this investigation, Aspergillus niger isolated from eight food substances, have been classified based on the absence of heterokaryon formation. The size of their sporangia were differentiated, the wild and mutant strains were subjected to vegetative compatibility tests in order to group them into different vegetative compatibility groups (VCGs) which include VCG-1, VCG-2, VCG-3 and VCG-4. The strains were further tested for the possible formation of a stable heterokaryon using nit mutants generated on potato dextrose agar (PDA) containing 2.5% chlorate (KClO3), represented as PDC. Based on the vegetative compatibility groups, nit mutants were paired on a minimal medium (MM) for complementation test. Interestingly, there was compatibility with mycelia showing anastomoses but without the formation of heterokaryon. The vegetative compatibility groups suggested four genotypes and polymorphism in the het loci. A population study for detailed genotyping is suggested in order to unravel the genetic recombination in A. niger.

scholarly journals Vegetative Compatibility Groups of Fusarium oxysporum f. sp. cepae from Onion in Colorado

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 606-610 ◽  
Author(s):  
C. E. Swift ◽  
E. R. Wickliffe ◽  
H. F. Schwartz
Keyword(s):  
Fusarium Oxysporum ◽  
Minimal Medium ◽  
Potato Dextrose Agar ◽  
Vegetative Compatibility ◽  
Potassium Chlorate ◽  
Vegetative Compatibility Groups ◽  
Breeding For Resistance ◽  
Nit Mutants ◽  
Northern Regions

Nineteen isolates of Fusarium oxysporum f. sp. cepae recovered from diseased onions growing in the western, southern, and northern regions of Colorado were placed into vegetative compatibility groups (VCGs) based on pairing of complementary mutants. Pathogenic isolates from these regions were cultured on variations of potassium chlorate (1.5 or 3.0%) mutation media, potato dextrose agar (PDA), and minimal medium (MM) supplemented with L-asparagine and L-threonine. Chlorate PDA and 3% chlorate MM with L-threonine did not generate the nitrate nonutilizing (nit) mutants required, while MM with L-asparagine (1.5 and 3% chlorate) and MM with L-threonine (1.5% chlorate) generated complementary nit mutants required for compatibility pairings. Five VCGs of F. oxysporum cepae were identified. One VCG was present in all three regions of Colorado examined. Four VCGs were restricted to either western or eastern Colorado. Additional sampling and evaluation of a more diverse collection of F. oxysporum cepae isolates from other regions of onion production is needed to determine the diversity of this pathogen. Such information could assist in breeding for resistance to F. oxysporum cepae.

scholarly journals Vegetative Compatibility Groups and Parasexual Segregation in Colletotrichum acutatum Isolates Infecting Different Hosts

2011 ◽  
Vol 101 (8) ◽  
pp. 923-928 ◽  
Author(s):  
Claudinéia Conationi da Silva Franco ◽  
Juliane Rocha de Sant' Anna ◽  
Lúcia Jacovozzi Rosada ◽  
Edilson Nobuyoshi Kaneshima ◽  
José Renato Stangarlin ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Vegetative Compatibility ◽  
Colletotrichum Acutatum ◽  
Diploid Strain ◽  
Alternative Source ◽  
Parasexual Cycle ◽  
Wild Isolate ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
First Time

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.

scholarly journals Characterization of Pyricularia grisea in the United States Using Independent Genetic and Molecular Markers

2000 ◽  
Vol 90 (12) ◽  
pp. 1396-1404 ◽  
Author(s):  
J. C. Correll ◽  
T. L. Harp ◽  
J. C. Guerber ◽  
R. S. Zeigler ◽  
B. Liu ◽  
...  
Keyword(s):  
United States ◽  
Mating Type ◽  
Population Data ◽  
The United States ◽  
Vegetative Compatibility ◽  
Dna Fingerprint ◽  
Pyricularia Grisea ◽  
Vegetative Compatibility Groups ◽  
Large Numbers ◽  
Nit Mutants

A total of 540 isolates of Pyricularia grisea from rice in the United States were examined for vegetative compatibility, MGR586 DNA fingerprint diversity, and mating type based on hybridization with the mat1-1 and mat1-2 sexual mating type alleles. The collections contained both archived and contemporary field isolates representative of the known MGR586 lineages and races that occur throughout the United States. Complementary nitrate nonutilizing (nit) or sulfate nonutilizing (sul) mutants were used to assess vegetative compatibility in P. grisea. There was a complete correspondence between vegetative compatibility groups (VCGs), MGR586 lineage, and mating type among 527 contemporary isolates (collected between 1991 and 1997) from Arkansas, Louisiana, Missouri, Mississippi, and Texas; all isolates in MGR586 lineages A, B, C, and D belonged to VCGs US-01, US-02, US-03, and US-04, respectively. In addition, all isolates tested in VCGs US-01 and US-04 had the mat1-1 mating type allele whereas those in VCGs US-02 and US-03 had the mat1-2 allele. The strict association of independent markers during this sample period was consistent with a strictly asexual mode of reproduction. However, examination of archived isolates collected in the 1970s and 1980s and contemporary isolates revealed an incongruent relationship between the independent markers. MGR586 C and E isolates were vegetatively compatible which indicated that multiple robust MGR586 delineated lineages could be nested within certain VCGs. Although isolates in lineages C and E were vegetatively compatible, they were of opposite mating type. Several hypotheses, including recombination, could account for the incongruence between the various markers. Among the eight MGR586 lineages (A through H) that occur in the United States, all isolates in lineages A, D, E, G, and H had the mat1-1 allele, whereas isolates in lineages B, C, and F had the mat1-2 allele. Nit mutants can be recovered relatively easy from P. grisea and should allow large numbers of individuals within a population to be assessed for vegetative compatibility. VCGs may prove to be an effective multilocus marker in P. grisea. Thus, VCGs should be a useful means for characterizing genetic structure in populations of the rice blast fungus worldwide, provide a useful genetic framework to assist in interpreting molecular population data, and may provide insight into potential sexual or asexual recombination events.

Classification of strains of Fusarium oxysporum on the basis of vegetative compatibility

1985 ◽  
Vol 63 (2) ◽  
pp. 179-183 ◽  
Author(s):  
John E. Puhalla
Keyword(s):  
Fusarium Oxysporum ◽  
Radial Growth ◽  
Minimal Medium ◽  
Evolutionary Model ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Vegetative Compatibility Groups ◽  
Heterokaryon Formation ◽  
Nit Mutants

Twenty-one strains of Fusarium oxysporum were classified on the basis of vegetative compatibility or the ability to form hetcrokaryons. Heterokaryon formation was demonstrated by pairing mutants that were unable to reduce nitrate. These "nit mutants" could be recovered without mutagen treatment from selective media containing KClO3. On Czapek's minimal medium the nit mutants had a radial growth rate like that of wild type, but their colonies were very thin. Two genetically different nit mutants were recovered in each of the 21 strains and paired in all combinations on minimal medium. Heterokaryon formation was indicated by dense growth where the two mutant colonies touched. As a result, 16 vegetative compatibility groups (VCGs) were defined such that only strains in the same VCG were vegetatively compatible. In no case was a strain assignable to more than one VCG. There was some evidence for a correlation between VCG and forma specialis. An evolutionary model to explain this correlation is proposed. Vegetative compatibility may be a fast and easy way to distinguish pathotypes of F. oxysporum.

scholarly journals Vegetative Compatibility Groups in Colletotrichum coccodes Subpopulations from Australia and Genetic Links with Subpopulations from Europe/Israel and North America

2010 ◽  
Vol 100 (3) ◽  
pp. 271-278 ◽  
Author(s):  
B. Ben-Daniel ◽  
D. Bar-Zvi ◽  
D. Johnson ◽  
R. Harding ◽  
M. Hazanovsky ◽  
...  
Keyword(s):  
Gene Flow ◽  
North America ◽  
The Netherlands ◽  
Vegetative Compatibility ◽  
Colletotrichum Coccodes ◽  
Vegetative Incompatibility ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
First Time ◽  
Limited Exchange

Vegetative compatibility of 94 isolates of Colletotrichum coccodes from Australia originating from potato, soil, and a weed (Solanum esuriale) was tested using nitrate-nonutilizing (nit) mutants. Isolates distributed to six vegetative compatibility groups (VCGs), five of them multimember (24.5, 23.4, 13.8, 12.8, and 7.5% distribution) and only one composed of two isolates (2.1%); 15.9% of them were not assigned to any of the VCGs. Aggressiveness of 51 isolates representing all six VCGs was tested by mature green tomato bioassay: isolates assigned to AUS-VCG-4 were the most aggressive and those in AUS-VCG-3 the least (P < 0.05). Isolates from warmer climates and lower latitudes were more aggressive (P < 0.05). In addition, we report for the first time complementations between isolates from Australia (AUS); North America (NA); and Israel, The Netherlands, Scotland, France, Germany (EU/I). Isolates assigned to AUS-VCG-4 anastomosed with isolates assigned to EU/I-VCG-7 and NA-VCG-5 (which also anastomosed with each other). Isolates assigned to EU/I-VCG-6 anastomosed with isolates assigned to NA-VCG-2 and isolates assigned to AUS-VCG-2 anastomosed with isolates assigned to EU/I-VCG-2. The linkage between subpopulations could result from the limited exchange of seed tubers among continents, or could be due to, for instance, gene flow, selection, or a limited number of polymorphic vegetative incompatibility genes.

scholarly journals Genetic Variability of Cercospora coffeicola from Organic and Conventional Coffee Plantings, Characterized by Vegetative Compatibility

2008 ◽  
Vol 98 (11) ◽  
pp. 1205-1211 ◽  
Author(s):  
R. B. Martins ◽  
L. A. Maffia ◽  
E. S. G. Mizubuti
Keyword(s):  
Genetic Variability ◽  
Production Systems ◽  
Diversity Index ◽  
Vegetative Compatibility ◽  
Cercospora Leaf Spot ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Geographical Regions ◽  
Minas Gerais State ◽  
Cercospora Coffeicola

Cercospora leaf spot is a destructive fungal disease that has become a threat to the coffee industry in Brazil. Nevertheless, little is known about populations of its causal agent, Cercospora coffeicola. We evaluated the potential of using nitrogen-nonutilizing (nit) mutants and vegetative compatibility groups (VCGs) to characterize the genetic variability of the C. coffeicola population associated with coffee plantings in Minas Gerais state (MG), Brazil. A total of 90 monosporic isolates were obtained from samples collected according to a hierarchical sampling scheme: (i) state geographical regions (Sul, Mata, and Triângulo), and (ii) production systems (conventional and organic). Nit mutants were obtained and 28 VCGs were identified. The 10 largest VCGs included 72.31% of all isolates, whereas each of the remaining 18 VCGs included 1.54% of the isolates. Isolates of the largest VCGs were found in the three regions sampled. Based on the frequencies of VCGs at each sampled level, we estimated the Shannon diversity index, as well as its richness and evenness components. Genetic variability was high at all hierarchical levels, and a high number of VCGs was found in populations of C. coffeicola associated with both conventional and organic coffee plantings.

scholarly journals Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae from Lettuce

Plant Disease ◽  
2005 ◽  
Vol 89 (3) ◽  
pp. 237-240 ◽  
Author(s):  
Matias Pasquali ◽  
Flavia Dematheis ◽  
Giovanna Gilardi ◽  
Maria Lodovica Gullino ◽  
Angelo Garibaldi
Keyword(s):  
Fusarium Oxysporum ◽  
Genetic Relatedness ◽  
The United States ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Group ◽  
Vegetative Compatibility Groups ◽  
Compatibility Group ◽  
Race 1

Fusarium oxysporum f. sp. lactucae, the causal agent of Fusarium wilt of lettuce, has been reported in three continents in the last 10 years. Forty-seven isolates obtained from infected plants and seed in Italy, the United States, Japan, and Taiwan were evaluated for pathogenicity and vegetative compatibility. Chlorate-resistant, nitrate-nonutilizing mutants were used to determine genetic relatedness among isolates from different locations. Using the vegetative compatibility group (VCG) approach, all Italian and American isolates, type 2 Taiwanese isolates, and a Japanese race 1 were assigned to the major VCG 0300. Taiwanese isolates type 1 were assigned to VCG 0301. The hypothesis that propagules of Fusarium oxysporum f. sp. lactucae that caused epidemics on lettuce in 2001-02 in Italian fields might have spread via import and use of contaminated seeds is discussed.

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