scholarly journals Molecular Identification of Two Vegetative Compatibility Groups of Fusarium oxysporum f. sp. cepae

2012 ◽  
Vol 102 (2) ◽  
pp. 204-213 ◽  
Author(s):  
Michael J. Southwood ◽  
Altus Viljoen ◽  
Glaudina Mostert ◽  
Adéle McLeod

Fusarium oxysporum f. sp. cepae, which causes basal rot of onion, consists of seven vegetative compatibility groups (VCGs 0420 to 0426) and several single-member VCGs (SMVs). F. oxysporum f. sp. cepae populations in South Africa and Colorado each consist of one main VCG (namely, VCG 0425 and 0421, respectively). The aim of this study was to develop sequence-characterized amplified region (SCAR) markers for the identification of VCGs 0425 and 0421, using 79 previously characterized F. oxysporum isolates. A second aim was to investigate the prevalence of VCG 0425 among 88 uncharacterized South African onion F. oxysporum isolates using (i) the developed SCAR markers and (ii) inter-retrotransposon (IR)- and random amplified polymorphic DNA (RAPD) fingerprinting. Only two RAPD primers provided informative fingerprints for VCG 0425 isolates but these could not be developed into SCAR markers, although they provided diagnostic fragments for differentiation of VCG 0425 from VCG 0421. IR fingerprinting data were used to develop a multiplex IR-SCAR polymerase chain reaction method for the identification of VCG 0421, VCG 0425, and SMV 4 isolates as a group. Molecular identification of the uncharacterized collection of 88 F. oxysporum isolates (65 F. oxysporum f. sp. cepae and 23 F. oxysporum isolates nonpathogenic to onion) confirmed that VCG 0425 is the main VCG in South Africa, with all but 3 of the 65 F. oxysporum f. sp. cepae isolates having the molecular characteristics of this VCG. Genotyping and VCG testing showed that two of the three aforementioned isolates were new SMVs (SMV 6 and SMV 7), whereas the third (previously known as SMV 3) now belongs to VGC 0247.

1999 ◽  
Vol 89 (2) ◽  
pp. 156-160 ◽  
Author(s):  
Jurriaan J. Mes ◽  
Emma A. Weststeijn ◽  
Frits Herlaar ◽  
Joep J. M. Lambalk ◽  
Jelle Wijbrandi ◽  
...  

A collection of race 1 and race 2 isolates of Fusarium oxysporum f. sp. lycopersici was screened for vegetative compatibility and characterized by random amplified polymorphic DNA (RAPD) analysis to establish the identity and genetic diversity of the isolates. Comparison of RAPD profiles revealed two main groups that coincide with vegetative compatibility groups (VCGs). In addition, several single-member VCGs were identified that could not be grouped in one of the two main RAPD clusters. This suggests that F. oxysporum f. sp. lycopersici is a polyphyletic taxon. To assign avirulence genotypes to race 1 isolates, they were tested for their virulence on a small set of tomato lines (Lycopersicon esculentum), including line OT364. This line was selected because it shows resistance to race 2 isolates but, unlike most other race 2-resistant lines, susceptibility to race 1 isolates. To exclude the influence of other components than those related to the race-specific resistance response, we tested the virulence of race 1 isolates on a susceptible tomato that has become race 2 resistant by introduction of an I-2 transgene. The results show that both line OT364 and the transgenic line were significantly affected by four race 1 isolates, but not by seven other race 1 isolates nor by any race 2 isolates. This allowed a subdivision of race 1 isolates based on the presence or absence of an avirulence gene corresponding to the I-2 resistance gene. The data presented here support a gene-for-gene relationship for the interaction between F. oxysporum f. sp. lycopersici and its host tomato.


Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 451-455 ◽  
Author(s):  
J. A. Gracia-Garza ◽  
D. R. Fravel ◽  
A. J. Nelson ◽  
K. S. Elias ◽  
B. A. Bailey ◽  
...  

Fusarium oxysporum f. sp. erythroxyli causes a vascular wilt of the narcotic plant coca (Erythroxylum coca var. coca). To determine whether this pathogen can be transmitted by infested seed, fruit from symptomatic and asymptomatic plants was collected from different coca-growing areas in Peru and from an experimental field site in Hawaii. A total of 202 fruit from Peru and 69 fruit from Hawaii were surface-disinfested and separated into five parts: pedicel, pericarp, seed coat, endosperm, and cotyledons. After the pedicel and pericarp were removed from the seed coat, the seed was surface disinfested again. Each fruit part was plated separately. Both F. oxysporum and F. moniliforme were recovered from fruit collected in Peru. Both species were isolated from all parts of some fruit. F. oxysporum was isolated from 33% of the fruit plated and most (35%) of these isolates were obtained from the seed coat. Slightly greater numbers of isolates (57%) were recovered from asymptomatic plants than from symptomatic plants (43%). Only F. oxysporum was isolated from fruit collected in Hawaii. Most of these isolates (59%) were from the pedicels of fruit collected from symptomatic plants. Out of 91 isolates of F. oxysporum, 21 were pathogenic to coca seedlings in a bioassay. Six of these pathogenic isolates were originally from the pedicel of the fruit, eight from the pericarp, four from the seed coat, and three from the endosperm. No isolates from the cotyledons were pathogenic. Most of the pathogenic isolates (76%) were from symptomatic plants. The pathogenic isolates were characterized using random amplified polymorphic DNA analysis and vegetative compatibility groups. Based on these analyses, two different subpopulations of the forma specialis erythroxyli were found in Peru, whereas only one was present in Hawaii. These data indicate that infested seed may contribute significantly to dissemination of this pathogen because seed is collected by growers and planted fresh or fermented briefly before planting.


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.


2007 ◽  
Vol 155 (1) ◽  
pp. 61-64 ◽  
Author(s):  
A. Catti ◽  
M. Pasquali ◽  
D. Ghiringhelli ◽  
A. Garibaldi ◽  
M. L. Gullino

2001 ◽  
Vol 79 (7) ◽  
pp. 836-843 ◽  
Author(s):  
S I Mpofu ◽  
K Y Rashid

Following the discovery of substantial differences in the development and severity of Fusarium wilt in Linum usitatissimum L. (flax) wilt nurseries in western Canada, a study of the population structure of Fusarium oxysporum f.sp. lini (Bolley) Snyd. & Hans using vegetative compatibility analysis was initiated. Vegetative compatibility was determined using nitrate non-utilizing mutants. From a total of 105 isolates, 74 were assigned to 12 vegetative compatibility groups (VCG 0440-04411), 22 were not compatible with any other isolates and 9 did not produce mutants. The populations of F. oxysporum f.sp. lini in Fusarium wilt nurseries in western Canada were significantly different. There was a predominant VCG in each of the nurseries, which was either nonexistent or not common in other nurseries, VCG 0440 in Indian Head, 0441 in Treherne, 0442 in Morden-80, 0443 in Saskatoon, and 0444 in Morden-60. There were only three overlapping VCGs; VCG 0440 was common to Morden-60 and Indian Head and VCGs 0442 and 0444 were common to Morden-60 and Morden-80. The differences in disease development and severity observed previously may be due to the differences in the population structure of the pathogen. These findings have significant implications for the approaches to breeding for Fusarium wilt resistance in flax.Key words: Fusarium oxysporum f.sp. lini, flax, Fusarium wilt, genetic diversity, vegetative compatibility.


1991 ◽  
Vol 69 (1) ◽  
pp. 168-172 ◽  
Author(s):  
T. R. Gordon ◽  
D. Okamoto

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.


HortScience ◽  
2017 ◽  
Vol 52 (11) ◽  
pp. 1483-1489 ◽  
Author(s):  
Kang Hee Cho ◽  
Seo Jun Park ◽  
Su Jin Kim ◽  
Se Hee Kim ◽  
Han Chan Lee ◽  
...  

Blueberry cultivars have traditionally been identified based on the evaluation of sets of morphological characters; however, distinguishing closely related cultivars remains difficult. In the present study, we developed DNA markers for the genetic fingerprinting of 45 blueberry cultivars, including 31 cultivars introduced from the United States Department of Agriculture. We obtained 210 random amplified of polymorphic DNA (RAPD) markers using 43 different primers. The number of polymorphic bands ranged from three (OPG-10 and OPQ-04) to eight (OPR-16), with an average of five. A cluster analysis performed with the unweighted pair group method using arithmetic averages produced genetic similarity values among the blueberry cultivars ranging from 0.53 to 0.85, with an average similarity of 0.68. A dendrogram clustered the 45 blueberry cultivars into two main clusters, with a similarity value of 0.65. Cluster I consisted of four rabbiteye cultivars (Pink Lemonade, Alapaha, Titan, and Vernon) and the Ashworth northern highbush cultivar. Cluster II consisted of 31 northern highbush cultivars, eight southern highbush blueberry cultivars, and Northland half-highbush blueberry cultivar. Fifty five RAPD fragments selected were sequenced to develop sequence-characterized amplified region (SCAR) markers, resulting in the successful conversion of 16 of 55 fragments into SCAR markers. An amplified polymorphic band has the same size as the RAPD fragment or smaller according to the primer combinations in the 16 SCAR markers. Among these markers, a combination of 11 SCAR markers provided sufficient polymorphisms to distinguish the blueberry cultivars investigated in this study. These newly developed markers could be a fast and reliable tool to identify blueberry cultivars.


1991 ◽  
Vol 69 (10) ◽  
pp. 2089-2094 ◽  
Author(s):  
Karol S. Elias ◽  
R. W. Schneider ◽  
M. M. Lear

A collection of 471 isolates of Fusarium oxysporum was obtained from symptomless tomato roots of plants grown at eight locations in Louisiana. Isolates that produced nitrate metabolism mutants (317 isolates) were included in an analysis of vegetative compatibility groups. One hundred and eighty-six isolates were assigned to 48 vegetative compatibility groups (2015–2062) containing 2–15 members from one to three different collection sites. Even though each site contained sub-populations of F. oxysporum common to other sites, only about half of the vegetative compatibility groups (21 groups) contained isolates from more than one site. In addition, there were 131 isolates of F. oxysporum that formed single-member vegetative compatibility groups. This diverse population composition is probably the result of several factors, including breeding strategies for resistance to fusarium wilt and tomato production practices in Louisiana. Resistance genes and horticultural traits from several sources (Lycopersicon spp.) have been incorporated into commercial tomato cultivars currently being grown. In addition, the long growing season in Louisiana allows several tomato cultivars containing different genes for resistance to be grown consecutively in the same field in a single year. Furthermore, other vegetable crops may be alternated with the tomato crops. Thus, the selection pressures that influence the composition of the nonpathogenic populations of F. oxysporum are in a constant state of flux. Key words: Fusarium oxysporum, genetic diversity, nonpathogens, vegetative compatibility groups.


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