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 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.

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 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 Vegetative Compatibility Groups and Pathogenicity Among Isolates of Fusarium oxysporum f. sp. cucumerinum

Plant Disease ◽  
1998 ◽  
Vol 82 (2) ◽  
pp. 244-246 ◽  
Author(s):  
Pyung Ahn ◽  
Hoo-Sup Chung ◽  
Yong-Hwan Lee
Keyword(s):  
Fusarium Oxysporum ◽  
Causal Agent ◽  
Vegetative Compatibility ◽  
Self Incompatibility ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Common Group

Seventy-eight isolates of Fusarium oxysporum f. sp. cucumerinum, the causal agent of cucumber wilt, were isolated from symptomatic tissues of cucumber from four provinces in Korea. These isolates were grouped into vegetative compatibility groups (VCGs) by demonstrating heterokaryosis by complementation tests using nitrate nonutilizing (nit) mutants. All isolates were grouped into six VCGs—1-A, 1-B, 1-C, 1-D, 1-E, and 1-F. No self-incompatibility was observed in any of the isolates tested. VCG 1-A was the most common group within growing regions in Korea and proved to be the most virulent of the VCGs identified. These data indicate that the level of virulence in F. oxysporum f. sp. cucumerinum is related to VCG.

scholarly journals Preliminary Characterization of Fusarium oxysporum f. sp. gladioli Causing Fusarium Corm Rot of Saffron in Italy

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 806-806 ◽  
Author(s):  
P. Di Primo ◽  
C. Cappelli
Keyword(s):  
Fusarium Oxysporum ◽  
Central Italy ◽  
Vegetative Compatibility ◽  
Crocus Sativus ◽  
Basal Stem Rot ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Rapid Spread ◽  
Plant Pathol

Fusarium corm rot of saffron (Crocus sativus L.), incited by Fusarium oxysporum Schlecht. f. sp. gladioli, causes severe stigma yield losses in L'Aquila Province in Central Italy. Primary symptoms during flowering (October through November) include basal stem rot, yellowing and wilting of shoots, and corm rot. The rapid spread of the disease is apparently caused only by movement of contaminated and/or infected corms (2,3). Ten isolates of F. oxysporum f. sp. gladioli, obtained from infected saffron crops located in the principal areas of saffron production in L'Aquila Province (2,3), were characterized by vegetative compatibility tests. The isolates were placed into vegetative compatibility groups (VCGs) using heterokaryon tests with chlorate-resistant nitrate-nonutilizing (nit) mutants. Based on complementation among these isolates and with a representative isolate of VCG 0340 (4), the tested isolates were assigned to VCG 0340. The fact that all isolates examined in this study belong to a single VCG supports the hypothesis that a clonal population of F. oxysporum f. sp. gladioli is spreading in L'Aquila Province in planting stock. In previous studies, only two Italian isolates of the pathogen obtained from Gladiolus were tested for vegetative compatibility, and both were included in VCG 0343 (1,4). Acquisition of further information on a larger number of isolates obtained from other cropping sites and associated with other hosts may result in a better understanding of the origin and spread of the pathogen in Italy, leading to improved strategies for control of Fusarium corm rot of saffron. References: (1) R. P. Baayen et al. Eur. J. Plant Pathol. 104:887, 1998. (2) C. Cappelli and G. Di Minco. Infitore Fitopatol. 49:27, 1999. (3) C. Cappelli and G. Di Minco. J. Plant Pathol. 80:253, 1998. (4) J. J. Mes et al. Plant Pathol. 43:362, 1994.

Vegetative compatibility groups among nonpathogenic root-colonizing strains of Fusarium oxysporum

1986 ◽  
Vol 64 (10) ◽  
pp. 2358-2361 ◽  
Author(s):  
J. C. Correll ◽  
J. E. Puhalla ◽  
R. W. Schneider
Keyword(s):  
Fusarium Oxysporum ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Production Areas ◽  
Apparently Healthy

A total of 110 isolates of Fusarium oxysporum were collected from apparently healthy celery roots from the major celery production areas of California. All isolates used in this study were nonpathogenic on celery. Nitrate-nonutilizing mutants (nit mutants) were used to test for vegetative compatibility among the isolates. Twenty-eight isolates were randomly selected from the collection and used as tester isolates. Complementary nit mutants, arbitrarily designated nitA and nitB, were recovered from each of the 28 tester isolates and paired in all combinations to test for vegetative compatibility among the isolates. Fourteen distinct vegetative compatibility groups, designated VCG2001 through VCG2014, were recovered. The remaining 82 isolates were then tested for vegetative compatibility with these 14 vegetative compatibility groups. Fifty of the 110 isolates belong to one of the 14 vegetative compatibility groups. Two vegetative compatibility groups, VCG2001 and VCG2002, were found in the highest frequency and from the most fields. The data suggest that some vegetative compatibility groups found colonizing celery roots may be much more common than others. Vegetative compatibility may be a way to identify and characterize strains of nonpathogenic F. oxysporum.

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.

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