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 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.

Vegetative compatibility groupings in a local population of Fusarium oxysporum

1991 ◽  
Vol 69 (1) ◽  
pp. 168-172 ◽  
Author(s):  
T. R. Gordon ◽  
D. Okamoto
Keyword(s):  
Fusarium Oxysporum ◽  
Key Words ◽  
Local Population ◽  
San Joaquin Valley ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Heterokaryon Formation ◽  
Pathogenicity Tests

One hundred isolates of Fusarium oxysporum collected from soil in the San Joaquin Valley in 1988 were tested for their ability to form intra- and inter-isolate heterokaryons. Five thousand and fifty isolate combinations were tested for vegetative compatibility, using complementary nitrate nonutilizing mutants. Ninety-eight combinations (2%) produced weakly positive reactions, 248 (5%) produced strong reactions, and 4704 combinations (93%) were negative for heterokaryon formation. This result suggests that anastomosis occurs infrequently among isolates in this population. Isolates were assigned to vegetative compatibility groups based on strong reactions. By this procedure 100 isolates were placed in 29 vegetative compatibility groups. At least one isolate from each of the 29 vegetative compatibility groups was tested and found to be vegetatively incompatible with the muskmelon wilt pathogen, F. oxysporum f. sp. melonis, which occurs in the same field. Each of these isolates also was avirulent to muskmelon in greenhouse pathogenicity tests. Forty isolates of F. oxysporum were collected in 1989 and 32 (80%) were compatible with isolates collected in 1988. The remaining eight isolates represented eight different vegetative compatibility groups. Key words: anastomosis, fungi, heterokaryon.

scholarly journals Improved Medium for Selecting Nitrate-Nonutilizing (nit) Mutants of Verticillium dahliae

1997 ◽  
Vol 87 (10) ◽  
pp. 1067-1070 ◽  
Author(s):  
Nadia Korolev ◽  
Talma Katan
Keyword(s):  
Verticillium Dahliae ◽  
Minimal Medium ◽  
Vegetative Compatibility ◽  
Potassium Chlorate ◽  
Wild Type ◽  
Nit Mutants ◽  
Cornmeal Agar

Nitrate-nonutilizing (nit) mutants are commonly used to determine vegetative compatibility between isolates of Verticillium dahliae by complementation (heterokaryon) testing. These mutants emerge spontaneously as chlorate-resistant sectors growing out of partially restricted, wild-type colonies on chlorate-amended media. The commonly used chlorate media are based on minimal medium (MMC) or cornmeal agar (CMC), amended with potassium chlorate. nit mutants recovered on these media constituted 10 to 36%(on MMC) and 25 to 45%(on CMC) of the apparently resistant sectors. An improved water agar chlorate medium (WAC) is described that is more effective for selecting chlorate-resistant nit mutants. WAC medium consists of agar (2%), glucose (0.02%), and potassium chlorate (2 to 5%). On WAC, growth of most V. dahliae isolates was strongly inhibited, and 66 to 100%(average >80%) of the chlorate-resistant sectors formed were nit mutants. Most mutants were characterized as nit1, and about 6% as NitM.

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 Nitrate Non-Utilizing Mutants and Vegetative Compatibility Groups of Fusarium Proliferatum and F. Sacchari Isolated from Rice in the Peninsular Malaysia and Kalimantan, Indonesia

2009 ◽  
Vol 49 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Nur Izzati Mohd Zainudin ◽  
Nor Ismail ◽  
Nik Izham Mohamed Nor ◽  
Azmi Razak ◽  
Siti Mohd Sidique ◽  
...  
Keyword(s):  
Strong Correlation ◽  
Minimal Medium ◽  
Peninsular Malaysia ◽  
Fusarium Proliferatum ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Vegetative Compatibility Groups ◽  
Growth Types ◽  
Different Sources

Nitrate Non-Utilizing Mutants and Vegetative Compatibility Groups ofFusarium ProliferatumandF. SacchariIsolated from Rice in the Peninsular Malaysia and Kalimantan, IndonesiaA total of 26 isolates ofFusarium proliferatumandF. sacchariwere isolated from rice in the Peninsular Malaysia and Kalimantan, Indonesia. Spontaneous chlorate-resistant sectors (CRSs) were recovered from all wild type of bothFusariumspecies when cultured on two chlorate media. The non-utilizing (nit) mutants were generated ascrn(chlorate resistant, nitrate utilizing),nit1, nit3and nitM based on phenotyping growth-types on diagnostic media with different sources of nitrogen. Thenitmutants were paired on minimal medium (MM) for examining the vegetative compatibility. The majority ofnitmutants (32.3-46.5%) recovered werenit1.Eight and seven vegetative compatibility groups (VCGs) ofF. proliferatumandF. sacchariwere identified, respectively. The isolates ofF. proliferatumandF. sacchariwere genetically diverse as shown by the number and distribution of the VCGs. No strong correlation was observed between VCGs of both species and location.

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.

Variability in Fusarium oxysporum f.sp. cubense

1990 ◽  
Vol 68 (6) ◽  
pp. 1357-1363 ◽  
Author(s):  
R. C. Ploetz
Keyword(s):  
Fusarium Oxysporum ◽  
Population Biology ◽  
Potato Dextrose Agar ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Group ◽  
Panama Disease ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Compatibility Group ◽  
Time Required

A worldwide collection of 96 isolates of Fusarium oxysporum f.sp. cubense (incitant of fusarial wilt of banana or Panama disease) from 12 countries was used to assess population structure in the pathogen; isolates were diverse for vegetative compatibility (11 vegetative compatibility groups) and race-specific virulence (races 1, 2, and 4). Rates of radial growth on potato dextrose agar differed at temperatures ranging from 8–36 °C for isolates in different VCGs and races (P < 0.05). On a KClO3-amended medium used to generate nitrate-nonutilizing (nit) mutants, variability in chlorate (a toxic analog of nitrate) sensitivity and the time required before nit mutants arose on the medium (mutability) was related primarily to vegetative compatibility group. In addition, cultural morphology on modified Komada's medium and potato dextrose agar was related primarily to vegetative compatibility group, whereas race was not as consistently related to these traits. In studies on the population biology and diversity in F. oxysporum f.sp. cubense, vegetative compatibility was a more useful character than race. On the basis of these results, it is suggested that F. oxysporum f.sp. cubense has had diverse origins.

scholarly journals An efficient method for selecting stable tester strains of vegetative compatibility groups in Verticillium dahliae

2016 ◽  
Vol 56 (2) ◽  
pp. 163-166 ◽  
Author(s):  
Maria Rataj-Guranowska
Keyword(s):  
Verticillium Dahliae ◽  
Efficient Method ◽  
Common Knowledge ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Vegetative Compatibility Groups ◽  
Cross Reactions ◽  
Nit Mutants ◽  
Genetic Barriers ◽  
The Way

Abstract The way compatible pairs of nitrate non-utilizing mutants (nit) are selected is usually not explained and remains unclear whether these pairs are representative for an isolate or strain. In addition, tester strains of Verticillium dahliae vegetative compatibility groups (VCGs) cross-react with at least one pair of tester strains of another VCG, and although it is a common knowledge of scientists working with the fungus that reversion of nit mutants to wild type occurs far too often, this fact is rarely mentioned in papers. To overcome the above problems, a protocol was developed for the generation of large number of nit mutants from any given isolate and to ensure that compatible pairs of mutants are indeed stable and the most frequent within the putative tester mutants produced from each isolate. Thus, we provide a reproducible and objective way of selecting V. dahliae tester strains for each isolate and VCG. Although VC grouping is based on the formation of stable heterokaryons, we demonstrate in this work that cross-reactions cannot be eliminated and that strict genetic barriers between two main VCG groups are absent in V. dahliae.

Sign in / Sign up

Export Citation Format

Share Document