scholarly journals Characterization of a Regional Population of Fusarium oxysporum f. sp. niveum by Race, Cross Pathogenicity, and Vegetative Compatibility

2007 ◽  
Vol 97 (4) ◽  
pp. 461-469 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts

Eighty-eight isolates of Fusarium oxysporum f. sp. niveum, collected from wilted watermelon plants and infested soil in Maryland and Dela-ware, were characterized by cross pathogenicity to muskmelon, race, and vegetative compatibility. Four isolates (4.5%) were moderately pathogenic to ≥2 of 18 muskmelon cultivars in a greenhouse test, and one representative isolate also was slightly pathogenic in field microplots. The four isolates all were designated as race 2, and were in vegetative compatibility group (VCG) 0082. Of the 74 isolates to which a VCG could be assigned, 41 were in VCG 0080, the VCG distributed most widely; 27 were in VCG 0082, and were distributed in half of the 20 watermelon fields surveyed; and 6 were in the newly described VCG 0083, and were restricted to three fields. Among the isolates in VCG 0080, 8 were designated as race 0, 21 as race 1, and 12 as race 2. Of the isolates in VCG 0082, 6 were designated as race 0, 11 as race 1, and 10 as race 2. All isolates in VCG 0083 were designated as race 2. Isolates from more than one race within the same VCG or isolates from more than one VCG were recovered from single plants and fields. No differences in aggressiveness on differential watermelon cultivars were observed among isolates from different VCGs of the same race. A diverse association between virulence and VCG throughout the Mid-Atlantic region suggests that the pathotypes of F. oxysporum f. sp. niveum may be of local origin or at least long existent in the region.

1991 ◽  
Vol 39 (2) ◽  
pp. 161 ◽  
Author(s):  
NY Moore ◽  
PA Hargreaves ◽  
KG Pegg ◽  
JAG Irwin

The production of volatiles on steamed rice by Australian isolates of Fusarium oxysporum f. sp. cubense correlated well with race and vegetative compatibility group (VCG). All race 4 isolates (VCGs 0120, 0129) produced distinctive volatile odours which gave characteristic gas chromatograms where the num- ber of peaks equated to VCG. Race 1 (VCGs 0124, 0125) and race 2 (VCG 0128) isolates, as well as non-pathogenic isolates of F. oxysporum from the banana rhizosphere, did not produce detectable volatiles and gave chromatograms without significant peaks.


Plant Disease ◽  
2000 ◽  
Vol 84 (3) ◽  
pp. 231-234 ◽  
Author(s):  
W. Schreuder ◽  
S. C. Lamprecht ◽  
G. Holz

Isolates of Fusarium oxysporum f. sp. melonis (72 total) obtained from 30 fields in 17 melonproducing regions in South Africa were race typed, using differential cvs. CM 17187, Doublon, Perlita, and Topmark, and grouped on the basis of vegetative compatibility. Fifty-four isolates were identified as race 0, eight as race 1, and ten as race 2. Race 0 occurred in 15 of 17 regions, whereas race 1 was sporadically recovered. Race 2 was obtained from only four fields located in one geographic region. Perlita plants (carrying the gene Fom3) inoculated with local isolates of races 0 and 2 and reference isolates of race 0 became stunted, and their leaves became yellow, thickened, and brittle. Using two inoculation methods, similar symptoms were induced by reference and local isolates of race 0 on Perlita seedlings. The results indicated that Fom3 in Perlita confers a tolerant reaction compared with the resistant reaction of gene Fom1 in Doublon and, therefore, should not be used alone in race determination tests. All isolates belonged to vegetative compatibility group 0134, indicating a high degree of genetic homogeneity among the South African F. oxysporum f. sp. melonis population.


Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 645-649 ◽  
Author(s):  
D. J. Vakalounakis ◽  
Z. Wang ◽  
G. A. Fragkiadakis ◽  
G. N. Skaracis ◽  
D.-B. Li

Thirty-four isolates of Fusarium oxysporum, obtained in China from cucumber plants showing either Fusarium wilt (F. oxysporum f. sp. cucumerinum) or root and stem rot (F. oxysporum f. sp. radicis-cucumerinum) symptoms, were characterized by pathogenicity, vegetative compatibility, and random amplified polymorphic DNA (RAPD). Of these, 23 isolates were identified by pathogenicity as F. oxysporum f. sp. cucumerinum, and one as F. oxysporum f. sp. radicis-cucumerinum, while 10 isolates were avirulent on cucumber, melon, sponge gourd, and pumpkin. The Chinese isolates of F. oxysporum f. sp. cucumerinum were assigned to RAPD groups III and XXI and to vegetative compatibility group (VCG) 0183, four new VCGs, 0184 to 0187, and a single-member VCG included in the artificial VCG 018-. The Chinese isolate of F. oxysporum f. sp. radicis-cucumerinum was assigned to RAPD group I and bridging VCG 0260/0261. The occurrence of F. oxysporum f. sp. radicis-cucumerinum on cucumber is reported for the first time in China.


Plant Disease ◽  
2005 ◽  
Vol 89 (3) ◽  
pp. 237-240 ◽  
Author(s):  
Matias Pasquali ◽  
Flavia Dematheis ◽  
Giovanna Gilardi ◽  
Maria Lodovica Gullino ◽  
Angelo Garibaldi

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.


2003 ◽  
Vol 93 (8) ◽  
pp. 1014-1022 ◽  
Author(s):  
G. Cai ◽  
L. Rosewich Gale ◽  
R. W. Schneider ◽  
H. C. Kistler ◽  
R. M. Davis ◽  
...  

Thirty-nine isolates of Fusarium oxysporum were collected from tomato plants displaying wilt symptoms in a field in California 2 years after F. oxysporum f. sp. lycopersici race 3 was first observed at that location. These and other isolates of F. oxysporum f. sp. lycopersici were characterized by pathogenicity, race, and vegetative compatibility group (VCG). Of the 39 California isolates, 22 were in VCG 0030, 11 in VCG 0031, and six in the newly described VCG 0035. Among the isolates in VCG 0030, 13 were race 3, and nine were race 2. Of the isolates in VCG 0031, seven were race 2, one was race 1, and three were nonpathogenic to tomato. All six isolates in VCG 0035 were race 2. Restriction fragment length polymorphisms (RFLPs) and sequencing of the intergenic spacer (IGS) region of rDNA identified five IGS RFLP haplotypes, which coincided with VCGs, among 60 isolates of F. oxysporum from tomato. Five race 3 isolates from California were of the same genomic DNA RFLP haplotype as a race 2 isolate from the same location, and all 13 race 3 isolates clustered together into a subgroup in the neighbor joining tree. Collective evidence suggests that race 3 in California originated from the local race 2 population.


1991 ◽  
Vol 37 (9) ◽  
pp. 669-674 ◽  
Author(s):  
K. F. Toth ◽  
M. L. Lacy

Vegetative compatibility grouping and electrophoretic separation of total proteins were compared as possible techniques for identifying isolates of Fusarium oxysporum f.sp. apii race 2, the cause of fusarium yellows of celery. Vegetative compatibility grouping was determined by pairing chlorate-tolerant, nitrate-nonutilizing mutants on a minimal medium containing nitrate as the sole nitrogen source. Heterokaryon formation, which resulted in wild-type growth, occurred only between mutants from vegetatively compatible isolates. All isolates of F. oxysporum f.sp. apii race 2 examined were placed within a unique vegetative compatibility group that excluded F. oxysporum f.sp. apii race 1 and the 11 other formae speciales of F. oxysporum tested. Few differences were observed in protein banding patterns among isolates of F. oxysporum f.sp. apii race 2, F. oxysporum f.sp. apii race 1, 11 other formae speciales of F. oxysporum, and 2 formae speciales of F. solani on 12% polyacrylamide gels. No banding pattern unique to F. oxysporum f.sp. apii race 2 was observed. Vegetative compatibility grouping could be accomplished more rapidly than greenhouse pathogenicity tests and more accurately identified race 2 isolates in a population of isolates of F. oxysporum from muck soils than did greenhouse pathogenicity tests or electrophoretic protein banding patterns. Key words: celery, fusarium yellows, nitrate-nonutilizing mutants, polyacrylamide gel electrophoresis.


Plant Disease ◽  
1998 ◽  
Vol 82 (5) ◽  
pp. 530-536 ◽  
Author(s):  
C. A. Clark ◽  
J-W. Hyun ◽  
M. W. Hoy

Thirty-five isolates of Fusarium oxysporum obtained from diseased sweetpotato or tobacco were compared for pathogenicity on two cultivars each of sweetpotato and tobacco, by random amplified polymorphic DNA (RAPD) profiles, and by vegetative compatibility group (VCG) analysis. Analysis of RAPD profiles revealed five clusters of isolates that corresponded to patterns of pathogenicity. One cluster of isolates, designated as F. oxysporum f. sp. nicotianae, induced severe wilting on both tobacco cultivars but varied from weakly to highly aggressive on the sweetpotato cultivars. Four of the 16 isolates from this group were originally isolated from sweetpotato, and 1 isolate caused severe disease on both crops. Three clusters included isolates from sweetpotato that were virulent on Porto Rico, caused little or no disease on Beauregard and burley tobacco (cv. Kentucky 5), and did not cause wilt on flue-cured tobacco (cv. Gold Dollar). These isolates were designated as race 0 of F. oxysporum f. sp. batatas. Isolates obtained from sweetpotato from California clustered separately from other sweetpotato isolates and the tobacco isolates. They differed from other sweetpotato isolates in being virulent on Beauregard and are proposed as a new race 1 of F. oxysporum f. sp. batatas. VCG analysis was of limited value with the isolates in this study because many isolates were self-incompatible. In each case, all members of a VCG fell within the same cluster defined by RAPDs. This study demonstrated that F. oxysporum from at least three genetically distinct lineages can cause Fusarium wilt on sweetpotato, and that the host ranges of F. oxysporum f. sp. batatas and F. oxysporum f. sp. nicotianae overlap and include plants from two different families.


Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1326-1332 ◽  
Author(s):  
Anthony P. Keinath ◽  
Richard L. Hassell

Fusarium wilt of watermelon, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. niveum race 2, is a serious, widespread disease present in major watermelon-growing regions of the United States and other countries. ‘Fascination,’ a high yielding triploid resistant to race 1, is grown in southeastern states in fields that contain a mixture of races 1 and 2. There is some benefit to using cultivars with race 1 resistance in such fields, even though Fascination is susceptible to Fusarium wilt caused by race 2. Experiments in 2012 and 2013 were done in fields infested primarily with race 2 and a mixture of races 1 and 2, respectively. Fascination was grafted onto four rootstock cultivars: bottle gourd (Lagenaria siceraria) ‘Macis’ and ‘Emphasis’ and interspecific hybrid squash (Cucurbita maxima× C. moschata) ‘Strong Tosa’ and ‘Carnivor.’ Nongrafted and self-grafted Fascination were used as susceptible control treatments. In both experiments, mean incidence of plants with symptoms of Fusarium wilt was ≥52% in the susceptible control treatments and ≤6% on the grafted rootstocks. Disease incidence did not differ between rootstock species or cultivars. In both years, Fascination grafted onto Strong Tosa and Macis produced more marketable-sized fruit than the susceptible control treatments. Grafted Emphasis and Carnivor also produced more fruit than the control treatments in 2012. The cucurbit rootstocks suppressed Fusarium wilt caused by race 2 and increased marketable yield of triploid watermelon grown in infested soil.


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