Academic literature on the topic 'Fusarium orthoceras'

Sugar beet (Beta vulgaris L.) - one of the most important crop in the world. In Kazakhstan, it is a traditional and major source of domestic sugar. The industry of cultivation and production of sugar beet is one of the priority areas of agricultural development of the country. In this paper, we studied the regeneration ability of different genotypes of sugar beet explants on selective media with the culture filtrate of the pathogen fungus F. oxysporum var. orthoceras. From the roots and shoots of sugar beet the pathogen Fusarium root rot was isolated. Was obtained pure cultures of the isolated pathogen. As a result, of morphological and cultural descriptions, as well as microbiological analysis it was revealed that the isolated pathogen is Fusarium Oxysporum. The results showed the pathogenicity of the fungus. For regeneration in vitro of the sugar beet genotypes resistant to the pathogen the culture media was optimized to the culture filtrate of the fungus F. oxysporum var. orthoceras. The frequency of shoot regeneration, depending on the genotype, was 1,0-12,5 %. On these explants the multiple shoot formations were observed.

Abstract The study of prevalence and species composition of Fusarium fungi on sunflower and winter wheat crops was carried out in Tambov region. In 1992-2020, 15 Fusarium fungi were identified on sunflower crops. It was identified that the predominant species infecting sunflower plants and seeds are Fusarium oxysporum, F. oxysporum var. orthoceras, F. verticillioides, and F. tricinctum. The prevalence of these pathogens was 16.3-21.8%. On the grain of winter wheat, Fusarium poae, F. equiseti and F. sporotrichioides were more common (19.6-28.6%). It was found that the seeds of Lgovskaya 8, Don Awnless and Don’s Governor were less affected by fusarium infection (by 3 - 4%). It was observed that Fusarium fungi are associated with certain winter wheat varieties. Research results may be useful for specialists studying diseases of sunflower and wheat.

The antifungal activity of the Bacillus bacteria is based on their ability to produce metabolites. Therefore, when selecting a strain that produces an effective biofungicide, it is necessary to assess the metabolism of bacteria. The aim of this work is to isolate exo- and endometabolites of the promising B. velezensis BZR 336g and B. velezensis BZR 517 strains and assess their antifungal activity. Studies were carried out in 2020–2021. The object of the study is a liquid culture of the B. velezensis BZR 336g and B. velezensis BZR 517 strains. Methods of liquid extraction, ascending thin layer chromatography (TLC), bioautography with a test-culture of Fusarium oxysporum var. orthoceras and Alternaria sp. fungi were used to analyze metabolites. The ability of the strains to accumulate a complex of active metabolites showing antifungal effect from fungistatic to fungicidal action was revealed. On the bioautogram of exometabolites, we found two most pronounced zones (Rf 0.18 and 0.29) of Fusarium oxysporum var. orthoceras BZR P1 growth inhibition (fungicide). Zones with Rf 0.58 for B. velezensis BZR 336g and Rf 0.70 for B. velezensis BZR 517 correspond to the test fungus growth retardation (fungistatic). Significant suppression of Alternaria sp. BZR P8 growth was also observed in two zones (Rf 0.18 and 0.29). The use of surfactin, iturin A, fengycin (Sigma-Aldrich®) in the TLC analysis made it possible to detect similar lipopeptides in the composition of metabolite complexes produced by the studied bacteria. It should be noted that the studied strains differed both in their ability to produce metabolites of different structure (can be found when analyzing chromatograms under ultraviolet light) and in their effect on phytopathogenic fungi in vitro. This may indicate possible differences in the mechanism of antagonistic activity of bacteria against phytopathogenic fungi. Thus, B. velezensis BZR 336g and B. velezensis BZR 517 produce a significant set of antifungal metabolites and can be used as strains to produce effective biofungicides.

The search of perspective strains-producers for microbiopreparations creation protecting oil flax of fusariose pathogen have been conducting in the laboratory of Biological methods of the V.S. Pustovoit All-Russian Research Institute of Oil Crops in recent years (2018–2020). These researches contemplate studying of a mode of antagonistic action of the promising strains-producers of microbiopreparations on a disease pathogen. There is presented an interaction between the promising strain-antagonist 11-3 Bacillus sp. selected by a stage screening and the pathogen Fusarium oxysporum var. orthoceras. Modifications of pathogen mycelium were stated at the second day of joint incubation, even before intergrowth with antagonist’s colony. They were as following: formation of spheroplasts (ball-shaped swellings of apical parts of hyphae), their explosion and lining appearance, and compression and discoloration of the separate mycelium plots. After intergrowth of pathogen and antagonist we noted the stronger compression, prolification, thickening and destruction of substrate airy mycelium and chlamidospores of fusariose pathogen. Pathogen’s mycelium at joint cultivation with the bacillary strain-antagonist was totally destructed at the eighth-tenth day.

To develop technological regimen for production of microbiopreparations in a preparation form ‘wetting powder’ we studied biological features and conditions of surface cultivating of a strain-producer Т-1 Trichoderma sp. – an antagonist of pathogen Fusarium oxysporum Schlecht. emend. Shyd. et Hans. var. orthoceras (App. еt Wr.) Bilai and Fusarium poae (Peck) Wollenw., Lewis on oil flax. To study cultural and physiological qualities of the strainproducer we used agar and liquid mediums. Surface cultivation of a fungus on agar and liquid Rudakov’s medium at a temperature 25–30 оС was the most favorable for mycelium growth and spore formation. Stationary fungus cultivation on liquid medium with рН from 3 to 6 provided maximal mycelium growth with spore formation and the highest dry mass. Addition of starch into the Chapek’s nutrient medium caused maximal growth of fungus mycelium and increase of its dry mass. The best source of nitrogen for a fungus strain was corn extract. Rudakov’s and No1 mediums are optimal compound liquid nutrient mediums for a surface cultivation of the strain-producer. Optimal period of the surface cultivation of the fungal strain Т-1 Trichoderma sp. on liquid Rudakov’s nutrient medium was 10 days, and a volume of sowing culture to a nutrient medium – 2.0%.

Goal. To investigate the antagonistic activity of a new strain of Trichoderma viride F-100076and its effect on the formation of micromycetes populations in the root zone of corn plants underfield conditions. Methods. The antagonistic activity of T. viride F-100076 was studied by the method of mixed (counter) cultures on wort agar using phytopathogenic fungi, which were isolated andidentified in the Laboratory of Plant-Microbial Interactions. The appearance and type of relationship were registered using a scale modified by Symonian and Mamikonian. The number of micromycetes was determined by the method of soil dilutions. Isolation, accounting and cultivation of fungiwas carried out according to conventional methods. Micromycetes were identified according to thedeterminants appropriate for a specific systematic group of micromycetes. Results. It was foundthat T. viride IMB F-100076 is characterized by high antagonistic activity against a wide range ofphytopathogenic fungi, showing hyperparasitism as early as on the eighth day. The highest antagonistic activity of the strain was found against: Alternaria radicina, Acremonium strictum, Acremonium сucurbitacearum, Fusarium oxysporum var. orthoceras, Fusarium moniliforme var. lactis, Torula expansa (5 points on the corresponding Symonian and Mamikonian scale). Data from the mycological analysis of the sod-podzolic soil of the corn rhizosphere showed that the mycocenosis ofthe sod-podzolic soil of the corn rhizosphere was formed by micromycetes belonging to the generaAcremonium Link, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which the most represented were micromycetes of the genus Penicillium (59 %). The total number of fungi in the control variant was291.00 ± 79.67 thousand CFU/g of soil. The introduction of straw affected both the total number ofmicromycetes and the genus composition of fungi. The total number of fungi in the variant withstraw increased 2.6 times and amounted to 744.00 ± 114.67 thousand CFU/g of soil. The number ofrepresentatives of all studied genera of micromycetes also increased. In addition, the introductionof straw provoked the development of fungi of Bipolaris and Fusarium genera, which can be considered a negative outcome since representatives of these species are commonly recognised as pathogens of root diseases. Application of the fungus antagonist T. viride IMB F-100076 to the soilalong with straw did not significantly affect the total number of micromycetes. At the same time, a displacement of fungi of the genus Bipolaris and Fusarium from the rhizosphere of corn was registered.The number of fusaria decreased from 96.00 ± 5.44 to 23.00 ± 2.32 thousand CFU/g of soil or almost4 times and reached the level of the control variant. Fungi of the genus Bipolaris in the variant withthe introduction of trichoderma were not detected. Conclusion. The antagonist fungus T. virideF-100076, introduced into the soil along with straw, strikes root in the soil and exhibits antagonisticactivity against micromycetes of the genera Bipolaris and Fusarium, which are commonly represented by root rot pathogens of many crops. Thus, the new strain T. viride F-100076 allows increasing theantagonistic potential of the rhizosphere soil of corn and protecting plants from pathogens.

We studied the antifungal activity of the Bacillus subtilis BZR 336g strain against the test culture of the fungus Fusarium oxysporum var. orthoceras App. et Wr. BZR 6, depending on the addition of citric acid crystalline hydrate, a microelements solution and corn extract to the liquid nutrient medium. It was found that citric acid at a concentration of 15 g/l improves the bioavailability of microelements and increases antifungal activity. Corn extract and microelements without the formation of a chelate form with citric acid do not affect the fungicidal properties of B. subtilis BZR 336g. However, the corn extract at a concentration of 3 g / l increases the titer of bacteria in the liquid culture from 2 ± 0.1 × 108 to 1 ± 0.08 × 108 CFU/ml. The combined use of the studied components allowed us to achieve a significant increase in the antifungal activity of B. subtilis BZR 336g by 3.1 times. At the same time, the effect of synergism in their complex interaction was noted, which is probably due to a qualitative and quantitative change in the composition of B. subtilis BZR 336g antifungal metabolites.