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1.
Penicillium oxalicum , a biocontrol agent for Fusarium oxysporum f.sp. lycopersici , was tested for its ability to induce resistance against tomato wilt. P. oxalicum and F. oxysporum f.sp. lycopersici were placed at separate sites on tomato plants or in soil, avoiding a direct interaction between the fungi. P. oxalicum induced resistance as expressed by a reduction in disease severity, area under disease progress curve and stunting induced by the pathogen. P. oxalicum colonized the tomato rhizosphere during the experiments but it was not detected inside stems, demonstrating that P. oxalicum and Fusarium oxysporum f.sp. lycopersici remained spatially separated. Biological control was observed both in sensitive and 'resistant' cultivars, indicating the role of a general resistance mechanism. In both cultivars P. oxalicum treatment alone did not produce disease symptoms. Therefore P. oxalicum could be a suitable biocontrol agent in cases of cultivar resistance failure. These results suggest that P. oxalicum can trigger defence mechanisms in the plant.  相似文献   

2.
The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.  相似文献   

3.
ABSTRACT Tomato (Lycopersicon esculentum) plants of 'Lorena' were induced with a conidial suspension (10(7) conidia per ml) of Penicillium oxalicum before inoculation with Fusarium oxysporum f. sp. lycopersici, the wilt pathogen. Histological changes occurred in plants under both growth chamber and glasshouse culture conditions and there was a reduction of disease severity. In noninduced plants, the pathogen produced almost a complete loss of cambium (75 to 100% reduction), an increase in the number of bundles, and a decrease in the number of xylem vessels (20% reduction), in which the diameter also was reduced by 20 to 30% in hypocotyls and epicotyls. The percentage of vessels colonized by F. oxysporum f. sp. lycopersici was positively correlated to the area under the disease progress curve (AUDPC). However, plants induced with P. oxalicum showed less disease, did not lose the cambium, had a lower number of bundles, and had less vascular colonization by F. oxysporum f. sp. lycopersici (35 to 99%). These effects also were observed in 'Precodor', which is susceptible to races 1 and 2 of F. oxysporum f. sp. lycopersici, and partially in 'Ramón', which is resistant to both races. Renewed or prolonged cambial activity that led to the formation of additional secondary xylem could be one of the reasons for disease reduction in P. oxalicum-induced tomato plants.  相似文献   

4.
Katan T  Shlevin E  Katan J 《Phytopathology》1997,87(7):712-719
ABSTRACT Plants exhibiting symptoms of wilt and xylem discoloration typical of Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici were observed in greenhouses of cherry tomatoes at various sites in Israel. However, the lower stems of some of these plants were covered with a pink layer of macroconidia of F. oxysporum. This sign resembles the sporulating layer on stems of tomato plants infected with F. oxysporum f. sp. radicis-lycopersici, which causes the crown and root rot disease. Monoconidial isolates of F. oxysporum from diseased plants were assigned to vegetative compatibility group 0030 of F. oxysporum f. sp. lycopersici and identified as belonging to race 1 of F. oxysporum f. sp. lycopersici. The possibility of coinfection with F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. radicis-lycopersici was excluded by testing several macroconidia from each plant. Airborne propagules of F. oxysporum f. sp. lycopersici were trapped on selective medium in greenhouses in which plants with a sporulating layer had been growing. Sporulation on stems was reproduced by inoculating tomato plants with races 1 and 2 of F. oxysporum f. sp. lycopersici. This phenomenon has not been reported previously with F. oxysporum f. sp. lycopersici and might be connected to specific environmental conditions, e.g., high humidity. The sporulation of F. oxysporum f. sp. lycopersici on plant stems and the resultant aerial dissemination of macroconidia may have serious epidemiological consequences. Sanitation of the greenhouse structure, as part of a holistic disease management approach, is necessary to ensure effective disease control.  相似文献   

5.
Fungi known to produce lytic enzymes were used in an attempt to control wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (FOL). Some of the fungal species (Penicillium oxalicum, Penicillium purpurogenum and Aspergillus nidulans) damaged hyphae of FOL in vitro and reduced the numbers of microconidia in the soil. Treatments with fungi did not result in a reduction in either chlamydospores of FOL in soil or populations of FOL in the rhizosphere of tomato. P. oxalicum was the most effective agent of biocontrol, and it reduced disease severity in both non-autoclaved (20% decrease) and sterile soil. In sterile soil, P. oxalicum reduced disease with different levels of severity (27% decrease at high levels and 50% decrease at low levels). Disease control by A. nidulans and P purpurogenum was only achieved when disease severity was low in sterile soil (55% and 45%, respectively).  相似文献   

6.
European Journal of Plant Pathology - Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is one of the main diseases affecting tomato plants. Three races (races 1, 2 and 3) of the...  相似文献   

7.
Fusarium crown and root rot of tomatoes in the UK   总被引：1，自引：0，他引：1  
Fusarium crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 106 spores/plant applied at seed sowing killed 70–83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels.  相似文献   

8.
Journal of General Plant Pathology - Fusarium wilt of tomato, a disease caused by the soilborne fungus Fusarium oxysporum f. sp. lycopersici, causes major losses to tomato production. Chemical...  相似文献   

9.
ABSTRACT Histochemical staining, beta-glucuronidase (GUS) activity, or placing roots on agar were methods used to characterize interactions between the pathogenic fungus, Fusarium oxysporum f. sp. lycopersici, and the nonpathogenic biocontrol F. oxysporum strain 70T01 with respect to colonization behaviors, interaction sites, and population densities on tomato roots. Mycelia of strain 70T01, a genetic transformant expressing stable GUS activity, hygromycin B resistance, and effective disease control, were localized in epidermal and cortex cell layers of tomato roots in a discontinuous and uneven pattern. In contrast, mycelia of F. oxysporum f. sp. lycopersici were found in the vascular bundles. Thus, direct interactions between the two fungi likely happen in the root surface cell layers. Colonization density of strain 70T01 was related to the inoculation density but decreased with distance from the inoculation site. Host defense reactions, including increased cell wall thickness or papilla deposits, were adjacent to 70T01 hyphae. Experiments done in soil showed that strain 70T01 densities in roots were highest at inoculation zones and barely detectable for root segments more than 2 cm away from the inoculation sites. F. oxysporum f. sp. lycopersici densities were lowest at 70T01 inoculation zones and highest (>10 times) where strain 70T01 was not directly applied. Newly elongating roots where strain 70T01 did not reach were available for infection by the pathogen. The higher strain 70T01 density was always found when the plants were simultaneously infected by F. oxysporum f. sp. lycopersici, suggesting that F. oxysporum f. sp. lycopersici has as much influence in predisposing the plant to colonization by strain 70T01 as strain 70T01 has on providing disease protection against the pathogen.  相似文献   

10.
Tomato cultivar Moneymaker was independently inoculated with Alternaria alternata, Cunninghamella elegans, Fusarium culmorum, F. oxysporum f.sp. lycopersici, F. oxysporum f.sp. pisi and Stromatinia gladioli and analysed ultrastructurally. The extent and amount of superficial fungal growth on tomato roots was similar but C. elegans , a saprophyte, was exceptional in that hyphae were not closely appressed to plant surfaces and did not adhere to plant cell walls.
In general, the type of plant responses to fungal colonization and infection were similar in all of the interactions studied, with the exception of C. elegans which did not infect tomato root tissue. The failure to penetrate tomato roots by C. elegans may have been associated with the lack of hyphal adhesion to plant cell walls. Migration of cytoplasm and wall apposition/penetration papilla formation were regularly observed in tomato root tissue beneath appressed hyphae and at sites of fungal infection. Specific cellular reactions in the exodermis, namely the formation of wall 'inclusions' and appearance of 'sensitive' cells, indicated that exodermal cells were particularly responsive to fungal challenge.
Fusarium oxysporum f.sp. lycopersici , a pathogen of tomato, invaded tomato root tissue more extensively than the other fungi inoculated onto tomato roots. Infection of tomato by the other fungi studied was variable, and the extent and success of fungal invasion was tentatively associated with their necrotrophic capability and typical host range.  相似文献   

11.
The tomato line IRB-301-31, resistant to fusarium crown and root rot ( Fusarium oxysporum f.sp. radicis-lycopersici ) was crossed with two susceptible cultivars, Motelle and Earlypak No. 7. When F1, F2 and backcross progenies were inoculated at the one-leaf stage with a suspension of spores of the pathogen, all could be classified as either resistant (healthy) or susceptible (dead). The ratios of resistant to susceptible plants indicated that resistance was conferred by a single dominant gene, designated Fr1.  相似文献   

12.
ABSTRACT 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.  相似文献   

13.
为了筛选新的生防菌菌种资源,采用稀释涂布平板法从番茄植株中分离得到一株内生细菌wm031,采用平板对峙法研究其对病原菌的抑制效果,结合菌体特征、16S rDNA序列分析及生理生化指标,对其进行初步鉴定,明确分类地位,并采用温室栽培试验对其进行抗病效果初探。结果表明,该菌株对西瓜枯萎病菌具有显著拮抗作用,同时对油菜菌核病菌、小麦根腐病菌、小麦全蚀病菌、辣椒疫霉病菌、大蒜菌核病菌、水稻恶苗病菌、葡萄炭疽病菌和番茄枯萎病菌均具有广谱抗性。根据菌体特征、16S rDNA序列分析及生理生化指标的结果,初步鉴定该菌为特基拉芽胞杆菌Bacillus tequilens。该菌株能够在西瓜和水稻植株中稳定定殖。温室栽培试验表明,菌株wm031对西瓜枯萎病具有显著的防治效果74.6%,高出百菌清的防治效果14.1%,说明该菌株具有田间应用开发的潜力。  相似文献   

14.
ABSTRACT The tomato Fusarium resistance gene I-2 confers resistance to F. oxy-sporum f. sp. lycopersici race 2, which expresses the corresponding aviru-lence gene avrI-2. To elucidate the molecular basis of this gene-for-gene interaction, we initiated a search for the avrI-2 gene. Gamma irradiation mutagenesis, using (137)Cs, was performed to generate an avrI-2 mutant of F. oxysporum f. sp. lycopersici. To this end, a race 2 isolate was first transformed with a phleomycine resistance gene and a GUS marker gene in order to distinguish mutants from contaminating isolates. A total of 21,712 mutagenized colonies was tested for loss of avirulence on I-2-containing tomato seedlings. One mutant was selected that showed the expected loss of avirulence but, surprisingly, also showed reduced pathogenicity toward susceptible tomato plants. DNA analysis was subsequently used to visualize genomic changes in the mutant. Southern analysis on contour-clamped homogeneous electrophoretic field blots demonstrated a translocation of a 3.75-Mb chromosome in the mutant. Random amplified polymorphic DNA and amplified fragment length polymorphism analysis identified at least nine polymorphisms between the wild-type and mutant isolates. Most of these polymorphisms appeared as extra fragments in the mutant and contained repetitive DNA sequences.  相似文献   

15.
ABSTRACT 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.  相似文献   

16.
Two bacterial isolates, Bacillus megaterium (c96) and Burkholderia cepacia (c91), demonstrated to be antagonistic against Fusarium oxysporum f.sp. radicis-lycopersici , the causal organism of fusarium crown and root rot of tomato, were evaluated as biocontrol agents alone and when integrated with the fungicide carbendazim. In an initial screening, these isolates reduced disease incidence by 75 and 88%, respectively. In vitro , both biocontrol agents were highly tolerant to the fungicide carbendazim, commonly used to control fusarium diseases. Carbendazim reduced disease symptoms by over 50% when used at > 50  µ g mL−1, but had little effect at lower concentrations. Combination of the bacterial isolates and carbendazim gave significant ( P  ≤ 0·05) control of the disease when plants were artificially inoculated with the pathogen. Application of carbendazim at a low concentration (1  µ g mL−1) in combination with B. cepacia c91 reduced disease symptoms by 46%, compared with a reduction of 20% obtained with the bacterium alone and no control with the chemical treatment alone. A combination of B. megaterium c96 with an increased application rate of 10  µ g mL−1 carbendazim significantly reduced disease symptoms by 84% compared with inoculated controls and by 77% compared with carbendazim treatment alone. In this experiment, the integrated treatment also slightly outperformed application of 100  µ g mL−1 carbendazim, and bacteria applied without fungicide also provided good disease control.  相似文献   

17.

A study was carried out in microplots to evaluate the effect of fly ash on the plant growth and yield of tomato cultivars, Pusa Ruby, Pusa Early Dwarf and New Uday, and on wilt disease caused by Fusarium oxysporum f.sp. lycopersici . Fly ash was applied to soil by broadcast or in rows at the rate of 1, 2, 3 and 4 kg ash m-2 in place of inorganic fertilizers. In control plots, NPK (about 40 : 20 : 20 kg acre-1) and compost were added in place of fly ash. Ash application greatly increased the soil contents of P, K, B, Ca, Mg, Mn, Zn, carbonates, bicarbonates and sulphates. Plants grown in the ash-treated plots, especially at 3 or 4 kg dose, showed luxuriant growth and greener foliage, and plant growth and yield of the three cultivars were significantly increased in comparison with the plants grown in plots without fly ash. The wilt fungus, F. oxysporum f.sp. lycopersici at the inoculum level of 2 g plant-1 caused significant suppression of growth and yield in all three cultivars. Application of fly ash, however, checked the suppressive effect of the fungus, leading to a significant increase in the considered variables compared with the inoculated control. Soil population of the fungus (colony-forming units g soil-1) gradually decreased with an increase in ash dose. Row application was found to be relatively more effective in enhancing the yield of tomato cultivars and suppressing the wilt disease. The greatest increase in the yield of fungus inoculated and uninoculated plants due to broadcast or row application at 3 or 4 kg ash m-2 was recorded in tomato cv. Pusa Ruby (39 - 61 and 9 - 24%), followed by Pusa Early Dwarf (31 - 61 and 17 - 34%) and New Uday (21 - 35 and 4 - 22%).  相似文献   

18.
The reactions of several tomato cultivars and the genetic basis of resistance to an isolate of Alternaria alternata f. sp. lycopersici were examined. Among the 105 cultivars tested only two, Regal and Toper, were susceptible, while the remainder were highly resistant. The resistant cultivar ACE 55 VF (P;) was crossed with the susceptible cultivar Earlypak No. 7 (P1)- When F1, F2, F3, BC1, BC1 selfed, F2 X P2 and BC1P2 x P1 progenies were inoculated at the two-leaf stage with a suspension of spores of the pathogen, the ratios of resistant to susceptible plants indicated that resistance was conferred by a single dominant gene.  相似文献   

19.
Antifungal activity of bergenin, a constituent of Flueggea microcarpa   总被引：1，自引：0，他引：1  
The antifungal activity of bergenin against some plant pathogenic fungi, namely, Alternaria alternata , A. brassicae , A. carthami , Fusarium udum , F. oxysporum f.sp. ciceri , Curvularia lunata and Erysiphe pisi , was studied. Bergenin as its monosodium salt was effective against all the fungi and the effective dose for complete inhibition of spore germination varied from 15 μg mL−1 for F. udum to 125 μg mL−1 for E. pisi . Experiments on the effect of bergenin on powdery mildew development under glasshouse conditions revealed that it can control powdery mildew of pea at 2000 μg mL−1 by postinoculation treatment, the results being comparable with those of carbendazim (1000 μg mL−1) and wettable sulfur (2000 μg mL−1). It affected hyphal elongation and the number of primary and secondary branches.  相似文献   

20.
Rekah Y  Shtienberg D  Katan J 《Phytopathology》2000,90(12):1322-1329
ABSTRACT Fusarium oxysporum f. sp. radicis-lycopersici, the causal agent of Fusarium crown and root rot of tomato, and F. oxysporum f. sp. basilici, the causal agent of Fusarium wilt in basil, are soilborne pathogens capable of producing conspicuous masses of macroconidia along the stem. The role of the airborne propagules in the epidemics of the disease in tomato plants was studied. In the field, airborne propagules of F. oxysporum f. sp. radicis-lycopersici were trapped with a selective medium and their prevalence was determined. Plants grown in both covered and uncovered pots, detached from the field soil, and exposed to natural aerial inoculum developed typical symptoms (82 to 87% diseased plants). The distribution of inoculum in the growth medium in the pots also indicated the occurrence of foliage infection. In greenhouse, foliage and root inoculations were carried out with both tomato and basil and their respective pathogens. Temperature and duration of high relative humidity affected rate of colonization of tomato, but not of basil, by the respective pathogens. Disease incidence in foliage-inoculated plants reached 75 to 100%. In these plants, downward movement of the pathogens from the foliage to the crown and roots was observed. Wounding enhanced pathogen invasion and establishment in the foliage-inoculated plants. The sporulation of the two pathogens on stems, aerial dissemination, and foliage infection raise the need for foliage protection in addition to soil disinfestation, in the framework of an integrated disease management program.  相似文献   

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