Influence of Fusarium wilt resistant tomato cultivars on root colonization of the mutualistic endophyte Fusarium oxysporum strain 162 and its biological control efficacy toward the root-knot nematode Meloidogyne incognita

2008 ◽  
Vol 115 (6) ◽  
pp. 273-278 ◽  
Author(s):  
A. A. Dababat ◽  
M. E. Selim ◽  
A. A. Saleh ◽  
R. A. Sikora
Plant Disease ◽  
2018 ◽  
Vol 102 (9) ◽  
pp. 1820-1827 ◽  
Author(s):  
Anthony P. Keinath ◽  
Paula A. Agudelo

Interspecific hybrid squash (Cucurbita maxima × C. moschata ‘Strong Tosa’) and bottle gourd (Lagenaria siceraria ‘Macis’) rootstocks are resistant to Fusarium oxysporum f. sp. niveum but susceptible to Meloidogyne incognita (Southern root-knot nematode). Coinfection of Early Prolific Straightneck summer squash (C. pepo) with root-knot nematode and F. oxysporum f. sp. niveum has been reported to increase susceptibility to Fusarium wilt. The objectives of this study were to determine whether such an interaction occurred between M. incognita and F. oxysporum f. sp. niveum races 1 and 2 on Strong Tosa, Macis, and watermelon cultivars Fascination (resistant to race 1) and Tri-X 313 (susceptible to both races). Hosts were inoculated in a greenhouse with one of four pathogen treatments: F. oxysporum f. sp. niveum, M. incognita, both pathogens, or neither pathogen. Galling was present on ≥10% of the root systems of 90% of the plants inoculated with M. incognita. Bottle gourd had less galling than interspecific hybrid squash. Plants not inoculated with F. oxysporum f. sp. niveum did not wilt. Four weeks after inoculation, incidence and severity of Fusarium wilt and recovery of F. oxysporum did not differ for any hosts inoculated with F. oxysporum f. sp. niveum alone and F. oxysporum f. sp. niveum plus M. incognita (host–treatment interactions not significant). In general, Early Prolific Straightneck grouped with the F. oxysporum f. sp. niveum-resistant rootstocks when inoculated with F. oxysporum f. sp. niveum race 2 and with the susceptible watermelon when inoculated with race 1, regardless of inoculation with M. incognita. Recovery of F. oxysporum from stems of inoculated watermelon was greater than recovery from the other three hosts, regardless of nematode inoculation. In conclusion, our experiments do not support the hypothesis that resistance to F. oxysporum f. sp. niveum in cucurbit rootstocks or resistant watermelon cultivars would be compromised when M. incognita infects the roots.


Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1383-1390 ◽  
Author(s):  
Anthony P. Keinath ◽  
W. Patrick Wechter ◽  
William B. Rutter ◽  
Paula A. Agudelo

Interspecific hybrid squash (Cucurbita maxima × Cucurbita moschata) rootstocks used to graft watermelon (Citrullus lanatus var. lanatus) are resistant to Fusarium oxysporum f. sp. niveum, the fungus that causes Fusarium wilt of watermelon, but they are susceptible to Meloidogyne incognita, the southern root knot nematode. A new citron (Citrullus amarus) rootstock cultivar Carolina Strongback is resistant to F. oxysporum f. sp. niveum and M. incognita. The objective of this study was to determine if an interaction between M. incognita and F. oxysporum f. sp. niveum race 2 occurred on grafted or nongrafted triploid watermelon susceptible to F. oxysporum f. sp. niveum race 2. In 2016 and 2018, plants of nongrafted cultivar Fascination and Fascination grafted onto Carolina Strongback and interspecific hybrid squash cultivar Carnivor were inoculated or not inoculated with M. incognita before transplanting into field plots infested or not infested with F. oxysporum f. sp. niveum race 2. Incidence of Fusarium wilt and area under the disease progress curve did not differ when hosts were inoculated with F. oxysporum f. sp. niveum alone or F. oxysporum f. sp. niveum and M. incognita together. Fusarium wilt was greater on nongrafted watermelon (78% mean incidence) than on both grafted rootstocks and lower on Carnivor (1% incidence) than on Carolina Strongback (12% incidence; P ≤ 0.01). Plants not inoculated with F. oxysporum f. sp. niveum did not wilt. At the end of the season, Carnivor had a greater percentage of the root system galled than the other two hosts, whereas galling did not differ on Fascination and Carolina Strongback. F. oxysporum f. sp. niveum reduced marketable weight of nongrafted Fascination with and without coinoculation with M. incognita. M. incognita reduced marketable weight of Fascination grafted onto Carnivor compared with noninoculated, nongrafted Fascination. In conclusion, cucurbit rootstocks that are susceptible and resistant to M. incognita retain resistance to F. oxysporum f. sp. niveum when they are coinfected with M. incognita.


1987 ◽  
Vol 33 (5) ◽  
pp. 349-353 ◽  
Author(s):  
T. C. Paulitz ◽  
C. S. Park ◽  
R. Baker

Nonpathogenic isolates of Fusarium oxysporum were obtained from surface-disinfested, symptomless cucumber roots grown in two raw (nonautoclaved) soils. These isolates were screened for pathogenicity and biological control activity against Fusarium wilt of cucumber in raw soil infested with Fusarium oxysporum f. sp. cucumerinum (F.o.c.). The influence of three isolates effective in inducing suppressiveness and three ineffective isolates on disease incidence over time was tested. The effective isolates reduced the infection rate (R), based on linear regressions of data transformed to loge (1/1 – y). Effective isolate C5 was added to raw soil infested with various inoculum densities of F.o.c. In treatments without C5, the increase in inoculum densities of F.o.c. decreased the incubation period of wilt disease, but there was no significant difference in infection rate among the inoculum density treatments. Isolate C5 reduced the infection rate at all inoculum densities of F.o.c. Various inoculum densities of C5 were added to raw soils infested with 1000 cfu/g of F.o.c. In the first trial, infection rates were reduced only in the treatment with 10 000 cfu/g of C5; in the second trial, infection rates were reduced in treatments with 10 000 and 30 000 cfu/g of C5.


Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 948-956 ◽  
Author(s):  
Alois A. Bell ◽  
Robert C. Kemerait ◽  
Carlos S. Ortiz ◽  
Sandria Prom ◽  
Jose Quintana ◽  
...  

Locally severe outbreaks of Fusarium wilt of cotton (Gossypium spp.) in South Georgia raised concerns about the genotypes of the causal pathogen, Fusarium oxysporum f. sp. vasinfectum. Vegetative complementation tests and DNA sequence analysis were used to determine genetic diversity among 492 F. oxysporum f. sp. vasinfectum isolates obtained from 107 wilted plants collected from seven fields in five counties. Eight vegetative complementation groups (VCG) were found, with VCG 01117B and VCG 01121 occurring in 66% of the infected plants. The newly recognized VCG 01121 was the major VCG in Berrien County, the center of the outbreaks. All eight VCG resulted in significant increases in the percentages of wilted leaves (27 to 53%) and significant reductions in leaf weight (40 to 67%) and shoot weight (33 to 60%) after being stem punctured into Gossypium hirsutum ‘Rowden’. They caused little or no significant reductions in shoot weight and height or increases in foliar symptoms and vascular browning in a soil-infestation assay. Soil infestation with Meloidogyne incognita race 3 (root-knot nematode) alone also failed to cause significant disease. When coinoculated with M. incognita race 3, all VCG caused moderate to severe wilt. Therefore, the VCG identified in this study belong to the vascular-competent pathotype, and should pose similar threats to cotton cultivars in the presence of the root-knot nematode. Use of nematode-resistant cultivars, therefore, is probably the best approach to control the disease in Georgia.


2012 ◽  
Vol 102 (3) ◽  
pp. 260-266 ◽  
Author(s):  
A. Martinuz ◽  
A. Schouten ◽  
R. A. Sikora

The root-knot nematode, Meloidogyne incognita, is among the most damaging agricultural pests, particularly to tomato. The mutualistic endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium etli strain G12 (G12) have been shown to systemically induce resistance toward M. incognita. By using triple-split-root tomato plants, spatially separated but simultaneous inoculation of both endophytes did not lead to additive reductions in M. incognita infection. More importantly, spatially separated inoculation of Fo162 and G12 led to a reduction in Fo162 root colonization of 35 and 39% when G12 was inoculated on a separate root section of the same plant in two independent experiments. In an additional split-root experiment, spatial separation of Fo162 and G12 resulted in a reduction of Fo162 root colonization of approximately 50% over the water controls in two independent experiments. The results suggested that the suppressive activity of G12 on Fo162 and M. incognita is possibly related to the induction of specific plant defense mechanisms. Thus, although Fo162 and G12 have the ability to systemically repress M. incognita infection in tomato, they can be considered incompatible biocontrol agents when both organisms are present simultaneously on the same root system.


Pathogens ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 43 ◽  
Author(s):  
Arfe Castillo ◽  
Cecirly Puig ◽  
Christian Cumagun

Philippine banana is currently threatened by Fusarium oxysporum f. sp. cubense Tropical Race 4 (FocR4). This study investigated the use of Trichoderma harzianum pre-treated with Glomus spp, as a means of managing Fusarium wilt on young ‘Lakatan’ banana seedlings. Results showed that Glomus applied basally significantly improved banana seedling growth with increased increment in plant height and pseudostem diameter and heavier root weight. The application of Glomus spp. alone offered 100% protection to the ‘Lakatan’ seedlings against FocR4 as indicated by the absence of the wilting symptom. A combination of T. harzianum and Glomus spp. also gave significant effect against Fusarium wilt through delayed disease progression in the seedlings but was not synergistic. Competitive effects were suspected when application of the two biological control agents on banana roots was done simultaneously.


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