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AFLP analysis of Fusarium species in the section Sporotrichiella-evidence for Fusarium langsethiae as a new species.

Amplified fragment length polymorphism (AFLP) was applied to compare 100 isolates of Fusarium poae, Fusarium sporotrichioides, and Fusarium langsethiae. Comparison of fingerprints revealed several markers specific for each group of isolates. Cluster analysis showed a clear separation of F. poae from F. sporotrichioides and F. langsethiae. F. langsethiae isolates formed a rather homogeneous group separated from F. sporotrichioides. The AFLP data obtained support F. langsethiae as a new Fusarium species, for the time being in the section Sporotrichiella.

Cluster Analysis↗

Natural variation of ascospore and conidial germination by Fusarium verticillioides and other Fusarium species.

Fusarium verticillioides and other Fusarium species were examined for their spore germination phenotypes. In general, germinating spores of F. verticillioides formed germ tubes that immediately penetrated into agar. Such invasive germination was the predominant growth phenotype among 22 examined field isolates of F. verticillioides from a broad range hosts and locations. However, two of the field isolates were unique in that they formed conidial germ tubes and hyphae that grew along the surface of agar before penetration eventually occurred. Conidia of 22 other Fusarium species were assessed for their germination phenotypes, and only some strains of F. annulatum, F. fujikuroi, F. globosum, F. nygamai, and F. pseudoanthophilum had the surface germination phenotype (21% of the strains assessed). Sexual crosses and segregation analyses involving one of the F. verticillioides surface germination strains, NRRL 25059, indicated a single locus, designated SIG1 (surface vs. invasive germination), controlled the germ tube growth phenotypes exhibited by both conidia and ascospores. Perfect correlation was observed between an ascospore germination phenotype and the germination phenotype of the conidia produced from the resulting ascospore-derived colony. Recombination data suggested SIG1 was linked ( approximately 7% recombination frequency) to FPH1, a recently described locus necessary for enteroblastic conidiogenesis. Corn seedling blight assays indicated surface germinating strains of F. verticillioides were less virulent than invasively germinating strains. Assays also indicated pathogenicity segregated independently of the FPH1 locus. Invasive germination is proposed as the dominant form of spore germination among Fusarium species. Furthermore, conidia were not necessary for corn seedling disease development, but invasive germination may have enhanced the virulence of conidiating strains.

Crosses, Genetic↗

Potential use of antioxidants for control of growth and fumonisin production by Fusarium verticillioides and Fusarium proliferatum on whole maize grain.

The effect of interactions between two food grade antioxidants butylated hydroxyanisole (BHA) and propyl paraben (PP, 100, 200, 500 microg g(-1)) and water activity (a(w), 0.995, 0.98, 0.95) of irradiated maize on lag phase prior to growth, growth rate and fumonisin production by Fusarium verticillioides and Fusarium proliferatum was evaluated at 25 degrees C. Both antioxidants had an effect on growth characteristics, and fumonisin production. However, this was dependent on the dose used and the a(w) treatment. At 500 microg g(-1) BHA and PP increased the lag phase prior to growth, and reduced the growth rate of both Fusarium species significantly, especially at 0.95 a(w). Both antioxidants significantly reduced the production of fumonisin by both Fusarium species, especially at 0.98 and 0.95 a(w). These results suggest that these antioxidants have potential for treatment of maize grain for controlling growth of these mycotoxigenic species and prevent fumonisin accumulation.

Antioxidants↗

Onychomycosis caused by Fusarium solani and Fusarium oxysporum in São Paulo, Brazil.

Fusarium species are common soil saprophytes and plant pathogens that have been frequently reported as etiologic agents of opportunistic infections in humans. We report eight cases of onychomycosis caused by Fusarium solani (4) and Fusarium oxysporum (4) in São Paulo, Brazil. These species were isolated from toenails in all cases. The infections were initially considered to be caused by dermatophytes. The clinical appearance of the affected toenails was leukonychia or distal subungual hyperkeratosis with yellowish brown coloration. The eight cases reported here suggest that Fusarium spp. should be taken into consideration in the differential diagnosis of tinea unguium.

Adult↗

Ethylene production by ectomycorrhizal fungi, Fusarium oxysporum f. sp. pini, and by aseptically synthesized ectomycorrhizae and Fusarium-infected Douglas-fir roots.

The ectomycorrhizal fungi Cenococcum geophilum, Hebeloma crustuliniforme, and Laccaria laccata produced ethylene in vitro in modified Melin-Norkrans liquid medium only if amended with 2.5-10mM methionine; Pisolithus tinctorius failed to produce ethylene unless the cultures were renewed with fresh methionine-amended medium before ethylene assay. An additional 19 ectomycorrhizal fungi, plus five isolates of Fusarium oxysporum f. sp. pini, all produced ethylene in renewed and (or) nonrenewed media. Although the rates varied, ethylene production by many ectomycorrhizal fungi equaled that of Fusarium. Culture filtrates of H. crustuliniforme and L. laccata also evolved ethylene that was apparently of nonenzymatic origin. Ethylene was produced by aseptically grown Douglas-fir seedlings inoculated with C. geophilum, H. crustuliniforme, and L. laccata and appearance of ethylene coincided with the formation of mycorrhizae; production by P. tinctorius inoculated seedlings was inconsistent. Lateral root formation of Douglas-fir was stimulated by inoculation with C. geophilum, H. crustuliniforme, and L. laccata but was inhibited by P. tinctorius. Fusarium-inoculated seedlings produced more ethylene sooner than seedlings inoculated with mycorrhizal fungi. The disparity in the levels of ethylene associated with ectomycorrhiza formation compared with Fusarium infection suggests a possible differential role for ethylene in symbiotic and pathogenic fungus-host interactions.

Cells, Cultured↗

Fusarium as a pathogen. A case report of Fusarium sepsis and review of the literature.

Fusarium species are known to the dermatologist as cutaneous contaminants. Rarely they occur as pathogens. We report a case of disseminated Fusarium moniliforme in a 44-year-old patient with acute lymphocytic leukemia. We also review the previous reports of human Fusarium infections. The mycologic characteristics of Fusarium, including its nosologic and morphologic characteristics and its response to medications, are discussed.

Adult↗

pH regulation of recombinant glucoamylase production in Fusarium venenatum JeRS 325, a transformant with a Fusarium oxysporum alkaline (trypsin-like) protease promoter.

Fusarium venenatum (formerly Fusarium graminearum) JeRS 325 produces heterologous glucoamylase (GAM) under the regulation of a Fusarium oxysporum alkaline (trypsin-like) protease promoter. The glucoamylase gene was used as a reporter gene to study the effects of ammonium and pH on GAM production under the control of the alkaline protease promoter. Between pH 4.0 and 5.8, GAM production in glucose-limited chemostat cultures of JeRS 325 grown at a dilution rate of 0.10 h-1 (doubling time, 6.9 h) on (NH4)2SO4 medium increased in a linear manner with increase in pH. However, at pH 4.0 and below GAM production was almost completely repressed in glucose-limited chemostat cultures grown on (NH4)2SO4 or NaNO3 medium. Thus GAM production in JeRS 325 is regulated by culture pH, not by the nature of the nitrogen source in the medium. The difficulty of using unbuffered medium when investigating putative ammonium repression is also shown. The study demonstrates the potential for use of the alkaline protease promoter in F. graminearum for the production of recombinant proteins in a pH dependent man ner.

Cells, Cultured↗

A genetic and biochemical approach to study trichothecene diversity in Fusarium sporotrichioides and Fusarium graminearum.

The trichothecenes T-2 toxin and deoxynivalenol (DON) are natural fungal products that are toxic to both animals and plants. Their importance in the pathogenicity of Fusarium spp. on crop plants has inspired efforts to understand the genetic and biochemical mechanisms leading to trichothecene synthesis. In order to better understand T-2 toxin biosynthesis by Fusarium sporotrichioides and DON biosynthesis by F. graminearum, we compared the nucleotide sequence of the 23-kb core trichothecene gene cluster from each organism. This comparative genetic analysis allowed us to predict proteins encoded by two trichothecene genes, TRI9 and TRI10, that had not previously been described from either Fusarium species. Differences in gene structure also were correlated with differences in the types of trichothecenes that the two species produce. Gene disruption experiments showed that F. sporotrichioides TRI7 (FsTRI7) is required for acetylation of the oxygen on C-4 of T-2 toxin. Sequence analysis indicated that F. graminearum TRI7 (FgTRI7) is nonfunctional. This is consistent with the fact that the FgTRI7 product is not required for DON synthesis in F. graminearum because C-4 is not oxygenated.

DNA, Fungal↗

Influence of temperature on zearalenone production by regional strains of Fusarium graminearum and Fusarium oxysporum in culture.

Zearalenone production by Fusarium graminearum and Fusarium oxysporum was studied under two temperature conditions. Incubation at 25 degrees C for 4 weeks enhanced zearalenone synthesis, improving detection of zearalenone-producing strains of Fusarium oxysporum. Zearalenone production was either totally or partially inhibited when temperature was lowered to 12-14 degrees C during the last 2 weeks of incubation.

Culture Media↗

Colonisation and competitiveness of Aspergillus and Penicillium species on maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum.

The effects of different steady-state water activity levels (a(w), 0.93, 0.95 and 0.98) and temperature (15 and 25 degrees C) on colonisation patterns of Aspergillus and Penicillium spp., when colonising irradiated maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum were assayed in terms of populations (colony forming units, CFUs g grain(-1)), seed infection and colonisation rates. The activity of F. moniliforme and F. proliferatum in grain reduced the presence of Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus to some extent, particularly at 15 degrees C and higher water availabilities (0.95-0.98 a(w)). In contrast, colonisation patterns of Penicillium implicatum on maize grain were unaffected by either Fusarium spp. in terms of CFUs or seed infection. Correlations were made between CFUs, seed infection, growth rates and niche overlap indices and hyphal interactions to try and link key indicators of competitiveness and dominance by an individual species.

Aspergillus↗

[Occurrence of Fusarium species and their mycotoxins in corn silage. 5. Fusarium infestation in corn silage].

The internal mycoflora of silage maize plants was examined in several years. Average Fusarium infection of the maize plants was 10.4% and leaf sheaths and stalks were preferably colonized by the fungi. During the growing season an increase in total colonization of the maize plant by field fungi as well as by species of the genus Fusarium was observed 17 different Fusarium species were isolated from silage maize plants. Most frequently occurring species (more than 85%) in descending order were F. avenaceum, F. culmorum, F. equiseti, F. sporotrichioides, F. crookwellense, F. oxysporum, F. sambucinum var. coeruleum.

Animal Feed↗

Passage through alternative hosts changes the fitness of Fusarium graminearum and Fusarium pseudograminearum.

Species of the necrotrophic fungal pathogen Fusarium that cause head blight and crown rot of cereals including wheat also infect a number of alternative host plants. This raises the prospect of more damaging pathogen strains originating and persisting as highly successful saprophytes on hosts other than wheat. The immediate impact on pathogenic (aggressiveness) and saprophytic (growth rate and fecundity) behaviour of six isolates with low, moderate or high initial aggressiveness was examined in two species of Fusarium after their passage through 10 alternative plant hosts. One passage through alternative hosts significantly reduced the pathogenic fitness of most isolates, but this change was not associated with a concomitant change in their overall saprophytic behaviour. The overall weak association between aggressiveness, fecundity and growth rate both before and after passage through the alternative hosts indicate that pathogenic and saprophytic fitness traits may be independently controlled in both Fusarium species. Thus, there was no trade-off between pathogenic and saprophytic fitness in these necrotrophic plant pathogens.

Edible Grain↗

Production of vomitoxin on corn by Fusarium graminearum NRRL 5883 and Fusarium roseum NRRL 6101.

Two vomitoxin-producing isolates of Fusarium spp. were grown on cracked corn for 1 to 8 weeks at 15, 20, 25, 28, and 32 degrees C. Maximum production of vomitoxin by Fusarium graminearum Schw. NRRL 5883 occurred at 30 degrees C and 40 days, and that by Fusarium roseum Schw. NRRL 6101 occurred at 26 degrees C and 41 days. These optimum production points were determined from response surface contour graphs in relation to temperature and time. Only small amounts of vomitoxin were produced at 15 and 20 degrees C by each strain. A 133-microgram quantity of vomitoxin, with an indicated purity of 95%, was isolated per gram of corn fermented with F. graminearum NRRL 5883.

Fusarium↗

Effect of pseudobactin 358 production by Pseudomonas putida WCS358 on suppression of fusarium wilt of carnations by nonpathogenic Fusarium oxysporum Fo47.

Nonpathogenic Fusarium oxysporum Fo47b10 combined with Pseudomonas putida WCS358 efficiently suppressed fusarium wilt of carnations grown in soilless culture. This suppression was significantly higher than that obtained by inoculation of either antagonistic microorganism alone. The increased suppression obtained by Fo47b10 combined with WCS358 only occurred when Fo47b10 was introduced at a density high enough (at least 10 times higher than that of the pathogen) to be efficient on its own. P. putida WCS358 had no effect on disease severity when inoculated on its own but significantly improved the control achieved with nonpathogenic F. oxysporum Fo47b10. In contrast, a siderophore-negative mutant of WCS358 had no effect on disease severity even in the presence of Fo47b10. Since the densities of both bacterial strains at the root level were similar, the difference between the wild-type WCS358 and the siderophore-negative mutant with regard to the control of fusarium wilt was related to the production of pseudobactin 358. The production of pseudobactin 358 appeared to be responsible for the increased suppression by Fo47b10 combined with WCS358 relative to that with Fo47b10 alone.

Fusarium↗

Fumonisin B1 production by Fusarium moniliforme and Fusarium proliferatum as affected by cycling temperatures.

The effects of temperatures cycling between 5 and 20 degrees C, 10 and 25 degrees C, and 15 and 30 degrees C on the production of fumonisin B1 (FB1) and ergosterol by Fusarium moniliforme and Fusarium proliferatum on rice was studied. Temperatures were cycled at 12-h intervals by manually moving cultures from one temperature to another. Constant temperature incubation at 25 degrees C and a low temperature stress were compared with the cycling temperature incubations. Low temperature stress was achieved by incubating rice cultures at 25 degrees C for 2 weeks followed by 15 degrees C for 4 weeks. The maximum yields of FB1 were found to be 247 microg/g by F. moniliforme at temperatures that cycled between 10 and 25 degrees C after 2 weeks and 284 microg/g by F. proliferatum when the temperatures cycled between 5 and 20 degrees C after 6 weeks. Ergosterol content of the rice cultures was also monitored. Overall, the two Fusarium species showed differences in production of FB1 and ergosterol under the various temperature treatments. The most notable differences were that the temperature treatments that stimulated greatest FB1 production were different for each species: cycling temperatures between 10 and 25 degrees C for F. moniliforme and cycling temperatures between 5 and 25 degrees C for F. proliferatum. At most temperatures, F. proliferatum produced more ergosterol than F. moniliforme. Maximum production of ergosterol by F. proliferatum occurred at 6 weeks, with temperatures that cycled between 10 and 25 degrees C, whereas F. moniliforme produced maximum amounts of ergosterol at 6 weeks, with temperatures that cycled between 15 and 30 degrees C.

Carboxylic Acids↗

Effect of water activity and temperature on growth and the relationship between fumonisin production and the radial growth of Fusarium verticillioides and Fusarium proliferatum on corn.

The two major fumonisin-producing Fusarium species are Fusarium verticillioides and Fusarium proliferatum. The growth and fumonisin production of these two isolates on corn was studied at water activities (a(w)) between 0.860 and 0.975 and at temperatures between 15 and 30 degrees C. Growth rates (g, mm/day) were obtained by linear regression during the linear phase of growth. In general, growth rates for both isolates increased significantly (P < 0.05) with increases in a(w) and temperature. Both fumonisin production and radial growth (mycelial development) for both isolates increased with a(w) at all temperatures investigated, but the effect of temperature on this relationship was not obvious. The effect of temperature on fumonisin production at high a(w) values optimal for growth was only marginal, whereas at lower a(w) values the effect of temperature was more pronounced, with more fumonisin production occurring at temperatures not optimal for growth. The optimum temperature for fumonisin production was between 15 and 25 degrees C. For F. proliferatum, the optimum temperature for growth at all a(w) values, 30 degrees C, resulted in the poorest fumonisin production. For both isolates, the slowest initial rate of fumonisin production was at 15 degrees C, the temperature at which the slowest growth rates were obtained.

Animals↗

Interactions between root-knot nematode Meloidogyne javanica and Fusarium wilt disease, Fusarium oxysporum f.sp. Melonis in different varieties of melon.

Fusarium oxysporum f.sp. melonis and root-knot nematode (Meloidogyne javanica) are destructive pathogens on cucurbits in Varamin area of Iran. The interaction between two pathogens was studied on local melon cultivars, Garmsar and Sooski. Inoculum of Meloidogyne javanica was prepared on susceptible cultivar, Rutgers using single egg mass method in greenhouse. Inoculum of Fusarium oxysporum f.sp. melonis (race 1) was prepared using Richard solution. A concentration of 2 x 10(5) micro conidia of fungus and 2000, 3000, 4000, 5000 eggs of nematode was used in 1 kg of autoclaved soil. Plants were inoculated with nematode at 2-3 leave stage then with fungus 2 weeks after nematode inoculation. The experiment was conducted in factoriel design based on CRD with 20 treatments, including varieties in 2 levels (Garmsar and Sooski), nematode in 5 levels (0, 2000, 3000, 4000, 5000 eggs) and fungus in 2 levels (presence and absence) and 3 replicates. The index that evaluated were growth index including fresh and dry weight of shoot and root, height, Fusarium wilt index and root gall index. Results of this experiment showed that all of treatments comparison to control were significantly different (p = 0.05) in growth index. Combination of fungus and nematode (5000 eggs) caused the most decrease in growth index on Garmsar and Sooski.

Animals↗