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.

scholarly journals Vegetative Compatibility Groups of Verticillium dahliae in Israel: Their Distribution and Association with Pathogenicity

2000 ◽  
Vol 90 (5) ◽  
pp. 529-536 ◽  
Author(s):  
Nadia Korolev ◽  
Jaacov Katan ◽  
Talma Katan
Keyword(s):  
Verticillium Dahliae ◽  
Vegetative Compatibility ◽  
Phenotypic Traits ◽  
Vegetative Compatibility Groups ◽  
Foliar Symptoms ◽  
Nit Mutants ◽  
Cotton Plants ◽  
Temperature Responses ◽  
Black Beauty ◽  
Reference Strains

A collection of 565 isolates of Verticillium dahliae, recovered between 1992 and 1997 from 13 host plant species and soil at 47 sites in Israel, was tested for vegetative compatibility using nitrate-nonutilizing (nit) mutants. Three vegetative compatibility groups (VCGs) were found and identified as VCG2A (28 isolates), VCG2B (158 isolates), and VCG4B (378 isolates) by using international reference strains. One isolate was heterokaryon self-incompatible. Of the VCG2B isolates, 92% were recovered from the northern part of Israel and 90% of VCG4B isolates were recovered from the south, with some overlap in the central region. Isolates of the minor group VCG2A were geographically scattered among the two major VCGs. Isolates of the same VCG resembled one another more than isolates from different VCGs based on colony and microsclerotial morphology, temperature responses, and, partially, pathogenicity. Different pathotypes were defined among 60 isolates tested, using cotton (cv. Acala SJ-2) and eggplant (cv. Black Beauty) as differentials. All isolates in VCG2A and 86% of the isolates in VCG4B, irrespective of their origin, induced weak to moderate symptoms on cotton and moderate to severe symptoms on eggplant and were similar to the previously described cotton nondefoliating patho-type. In contrast, all cotton isolates in VCG2B caused severe foliar symptoms, stunting, and often death, but little or no defoliation of inoculated cotton plants. These were defined as a cotton defoliating-like pathotype and induced only weak to moderate symptoms on eggplant. We concluded that vegetative compatibility grouping of V. dahliae in Israel is closely associated with specific pathogenicity and other phenotypic traits.

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 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 Vegetative Compatibility Groups in Cercospora kikuchii, the Causal Agent of Cercospora Leaf Blight and Purple Seed Stain in Soybean

2005 ◽  
Vol 95 (3) ◽  
pp. 257-261 ◽  
Author(s):  
G. Cai ◽  
R. W. Schneider
Keyword(s):  
Leaf Blight ◽  
Vegetative Compatibility ◽  
The Other ◽  
Wild Type ◽  
Cercospora Kikuchii ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Pathogenicity Tests ◽  
Soybean Plants ◽  
Soybean Leaves

Nitrogen nonutilizing (Nit) mutants were used to assess vegetative compatibility of 58 isolates of Cercospora kikuchii, 55 of which were isolated from soybean plants in Louisiana. Two isolates were vegetatively self-incompatible. Of 56 self-compatible isolates, 16 were assigned to six multimember vegetative compatibility groups (VCGs), 01 to 06, with 2 or 3 isolates in each VCG. The other 40 isolates each belonged to a distinct VCG. All six multimember VCGs contained isolates from different soy bean cultivars, and three included isolates from different locations. Only one of six multimember VCGs included isolates both from soybean leaves and seed, while the other five included isolates from only leaves or seed. The likelihood of tissue specificity or preference was discussed. All isolates and tested Nit mutants produced cercosporin on potato dextrose agar under light. Significantly different amounts of cercosporin were produced among wild-type isolates, and two Nit mutants produced significantly more cercosporin than their wild-type counterparts. All isolates produced typical Cercospora leaf blight symptoms on soybean plants in greenhouse pathogenicity tests.

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 and Pathogenicity of Verticillium dahliae from Spearmint and Peppermint

Plant Disease ◽  
2001 ◽  
Vol 85 (3) ◽  
pp. 297-302 ◽  
Author(s):  
L. I. Douhan ◽  
D. A. Johnson
Keyword(s):  
United States ◽  
Verticillium Dahliae ◽  
Potato Cultivar ◽  
Washington State ◽  
Vegetative Compatibility ◽  
Midwestern United States ◽  
Vegetative Compatibility Groups ◽  
Russet Norkotah ◽  
Nit Mutants

The vegetative compatibility of 128 isolates of Verticillium dahliae from spearmint and peppermint in the western and midwestern United States was determined. Nit mutants were used to assign isolates to vegetative compatibility groups (VCGs). All isolates were assigned to VCG 2B except for one assigned to VCG 2A and two assigned to VCG 4A. VCG 2 isolates were found in all commercial mint growing regions, while the two VCG 4A isolates originated from southern Idaho. Pathogenicity assays on mint were performed using isolates from mint and other hosts, and pathogenicity assays were conducted on the potato cultivar Russet Norkotah using mint and potato isolates. Isolates originating from mint were significantly more aggressive on mint than were other host isolates, indicating that mint isolates were host-adapted. VCG 4A isolates from mint and potatoes were significantly more aggressive on potato than VCG 4B potato isolates and VCG 2B mint isolates. We speculate that the low VCG diversity of mint isolates may be due to the introduction of a single aggressive strain into Washington State mint fields via infected rhizomes.

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.

Pathogenicity and vegetative compatibility among isolates of Fusarium oxysporum and F. moniliforme colonizing asparagus tissues

1989 ◽  
Vol 67 (8) ◽  
pp. 2420-2424 ◽  
Author(s):  
J. A. LaMondia ◽  
W. H. Elmer
Keyword(s):  
Fusarium Moniliforme ◽  
Vegetative Compatibility ◽  
Asparagus Officinalis ◽  
Symptom Expression ◽  
Old Field ◽  
Storage Roots ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Compatibility Group ◽  
Stem Segments

Isolates of Fusarium moniliforme (Sheld.) emend. Snyd. & Hans., F. oxysporum (Schlecht) emend. Snyd. & Hans., and F. solani (Mart.) Appel & Wollenw. emend. Snyd. & Hans. were recovered from three 5-year-old field grown asparagus (Asparagus officinalis L. cv. Mary Washington) by isolating from symptomatic and asymptomatic feeder roots, storage roots, crown and basal stem segments. Fusarium moniliforme was more virulent than F. oxysporum on asparagus seedlings and F. solani was considered nonpathogenic. Isolates of F. moniliforme and F. oxysporum were placed into vegetative compatibility groups (VCGs) by demonstrating heterokaryosis with complementation tests using nitrate-nonutilizing (nit) mutants (pairing nitM and nit1 mutants). Ninety-seven of 135 isolates of F. moniliforme were placed in 13 vegetative compatibility groups. The remaining 38 isolates were not classified by vegetative compatibility because of poor nit mutant recovery. Eight of 18 isolates of F. oxysporum were unique and classed as single members of eight different VCGs. The other 10 isolates were not placed in VCGs. All isolates of F. moniliforme were virulent, but mean disease ratings differed among the isolates in different VCGs. There was no correlation between vegetative compatibility group and tissue substrate or symptom expression on the tissue substrate. It appears that virulence on asparagus is a common trait with few exceptions among genetically distinct populations of F. moniliforme and F. oxysporum colonizing asparagus.

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