The antagonistic activity of 23 strains of micromycetes belonging to different taxonomic groups, against phythopathogenic bacteria and fungi was studied. The antagonistic activity of the micromycetes was tested by agar diffusion (the method of blocks). For the determination of the influence of the micromycetes on plants, spring barley seeds were treated by cultural liquid of fungi (dilution 1 : 10) for 24 hours and germinated in Petri dishes on moist filter paper. Two strains Trichoderma longibrachiatum 17 and T. lignorum 14 showed the highest antagonistic activity against the phytopathogenic bacteria and fungi. T. longibrachiatum 17 actively suppressed the growth of fungi
Fruit crops of the genus Chaenomeles Lindl are considered today as a superfood due to accumulation of biologically active compounds with antioxidant ability and known health-promoting properties. Successful introduction of this non-traditional culture in the steppe zone of Ukraine characterised by an unfavourable climate suggests the functioning of effective protective mechanisms in plants, including those that can be provided by the influence of endophytic microorganisms. However, there is little information about the endophytic community of Chaenomeles plants. Herein, the current study was aimed to isolate the endophytic fungi from the Ch. speciosa fruits and evaluate their biological activities against the phytopathogens. The study was carried out based on the collection of the Botanical Garden of Oles Honchar Dnipro National University (Dnipro city, Ukraine). Three media, namely PDA, MPA, and Gause’s medium were used for isolation of endophytic fungi. Colonies of isolates for identification were grown on PDA, Czapek's agar, and Czapek’s yeast autolysate media. Six fungal endophytic isolates derived from both peel and pulp of Ch. speciosa fruits have been morphologically identified using macroscopic and microscopic techniques, and assigned to the genus Penicillium (sections Chrysogena, Penicillium, Viridicata), and genus Talaromyces (section Talaromyces). Species P. expansum, P. viridicatum, and P. hirsutum were identified among the peel isolates, while P. chrysogenum, P. cyclopium, and P. purpurogenum were among the pulp isolates. Antagonistic ability of the endophytic isolates against phytopathogenic fungi was evaluated using the dual culture method. The results showed moderate to high antifungal capacity of the endophytic isolates against the phytopathogenic strains of the Fusarium genus. The growth inhibition of F. culmorum mycelium due to the influence of endophytic isolates was 51.5–81.3%, and the inhibition of the growth of F. oxysporum colonies was in the range of 68.4–86.6% as compared with control. There were no significant differences in the antagonistic ability between endophytic isolates derived from the peel and pulp of the fruit. Taken together, our findings indicated the great potential of the endophytic fungi from Ch. speciosa fruits as a source for the development of biocontrol agents and discovery of new bioactive compounds.
Background Endophytes promote the survival of the host plants affected by unfavorable environment. To confirm the endophytes role in Chaenomeles speciosa pathogenic resistance, fungal isolates were derived from both fruit peel and pulp, and presumptively identified using macroscopic and microscopic techniques. Antifungal potential of the isolates was assayed by dual culture method and agar disc method against Alternaria alternata, Fusarium culmorum, and Fusarium oxysporum strains. Two most active fungal isolates were cultured in Czapek's liquid medium to obtain metabolites. The crude ethyl acetate extracts of metabolites were characterized for antibacterial activity against Basillus subtilis and Erwinia dissolvens, and for component composition by GC–MS technique. Results Nine fungal endophytic isolates were derived from the peel and pulp of C. speciosa fruits and tentatively attributed to Penicillium spp. (seven isolates), Aspergillus spp. (one isolate), Mucor spp. (one isolate). Two fungal isolates, one each of the fruit peel and pulp, were designated as Penicillium sp. I and Penicillium sp. II respectively, and selected for further research. Both isolates showed similar activity against A. alternata; however, Penicillium sp. I activity against F. culmorum and F. oxysporum exceeded the activity of Penicillium sp. II. Cultural medium ethyl acetate extracts of both endophytes exhibited higher antibacterial activity against Gram-positive B. subtilis, while mycelium extracts were more active against Gram-negative E. dissolvens. In general, Penicillium sp. I antibacterial activity was higher in cultural medium extracts, while activity of Penicillium sp. II dominated in mycelium extracts. GC–MS analysis of the fungal metabolites component composition revealed the identity of 27 and 17 compounds, respectively in the ethyl acetate extracts of Penicillium sp. I and Penicillium sp. II cultural medium. Basic compounds produced by the first isolate, were represented by 3-Furanacetic acid, 4-hexyl-2,5-dihydro-2,5-dioxo, Diisooctyl phthalate, 11-Hexadecyn-1-ol, and Propanedioic acid, dihydroxy. At the same time, Phthalic acid diisooctyl ester and other phthalates constituted the main part of the second isolate metabolites, followed by Hexadecanoic acid, Eicosyl isopropyl ether, and 4-Butoxy-2-butanone at a lower content. Conclusions The findings showed that the antimicrobial potential of Chaenomeles fruits endophytic fungi is promising and deserves further investigation.
We evaluated the antagonistic activity of 23 strains of Bacillus spр. against phytopathogenic fungi Fusarium oxysporum, F. culmorum, F. moniliforme, Cladosporium herbarum, Alternaria alternata and Aspergillus niger. The antagonistic activity was tested by agar diffusion (the method of blocks). For determining the influence of bacteria on barley plants , ardent seeds were treated by cultural liquid (dilution 1 : 10) for 2 hours and germinated in Petri dishes on moist filter paper. The fungistatic effect of Bacillus sрp. separately and in combination with entomopathogens (in equal ratio) was determined by the level of inhibition of the fungi Fusarium spp. on a solid nutrient medium with 5% of the culture liquid. Insecticidal activity of microorganisms was determined in the model experiments by the percentage of death of the caterpillar Archips podana Scop. Strains of Bacillus sp. KMB-3 and Bacillus sp. KMB-6 inhibited the growth of all test cultures (zones of growth inhibition 11.4–30.6 and 11.5–29.4 mm, respectively). We established the absence of antagonism between selected strains and entomopathogenic bacteria Bacillus thuringiensis IMB-7186, fungi Beauveria bassiana IMB-F-100043. We found that treatment of barley seeds with culture liquids of Bacillus sp. KMB-3 and Bacillus sp. KMB-6 didn’t have a negative effect on the morphometric indices and dry weight of seedlings. We established that the highest percentage of growth inhibition of F. culmorum IMB-F-50716 was provided by a complex of Bacillus sp. KMB-3, B. bassiana IMB-F-100043 and B. thuringiensis IMB-7186, whose action was at the same level as the action of monoculture Bacillus sp. KMB-3 (85.4% and 84.7%, respectively). The highest percentage inhibition of growth of F. oxysporum ІМВ-F-54201 was provided by a complex of strains of Bacillus sp. KMB-3 and B. bassiana IMB-F-100043, whose effect was slightly inferior to that of the monoculture Bacillus sp. KMB-3 (68.4% and 75.1%, respectively). The insecticidal activity of complexes Bacillus sp. KMB-3, B. bassiana IMB-F-100043, B. thuringiensis IMB-7186 or Bacillus sp. KMB-6, B. bassiana IMB-F-100043, B. thuringiensis IMB-7186 insignificantly differed from that of the complex entomopathogens B. bassiana IMB-F-100043 and B. thuringiensis IMB-7186 (71.1%, 73.3% death versus 80.0%). The selected microbial complexes can be considered as promising for the development of a preparation for the protection of plants against fungal diseases and harmful insects.
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