Biological activity assessment of museum cultures of antagonist microorganisms and their use for presowing treatment of Scots pine seeds (Pinus sylvestris L.) (in vitro)

The microbiological method is applied for the purpose of artificial forest regeneration, as the most effective method of protecting forest planting material grown in forest nurseries. At present, literature data contain many examples of using species and genera of microorganisms belonging to different taxa in order to protect plants. The aim of the research was to establish biological (antagonistic, enzymatic and growth-stimulating) activity of the museum microorganism cultures belonging to different taxonomic groups (bacteria, fungi), and to assess their influence on the growth and development of Scots pine seeds in vitro and a decrease in the number of phytopathogenic fungi. We isolated previously selected microorganisms from the nursery soils; these microorganisms belong to different taxonomic groups, namely, Trichoderma micromycetes (T. harzianum, T. longibrachaitum, and T. lignorum), Streptomyces lateritius bacteria, Bacillus amyloliquefaciens, as well as phytopathogenic Fusarium fungi (F oxysporum, F. moniliforme, F. proliferatum, F. moniliforme var annullatum, and F. oxysporum B3). Antagonistic activity of microbial strains was determined by the dual culture method, and the presence of enzymatic activity (lipase, proteinase and chitinase) of the tested strains was observed by qualitative express tests. We studied the growth-promoting activity by soaking pine seeds in aqueous suspensions of antagonists (10⁶ spores/ml) (Pegalado, 2000; Cullimore, 2001; Montealegre, 2003; Asaturova, 2012). The results of the research showed that the investigated microorganisms (fungi, actinobacteria and bacteria) are biologically active. The most powerful antagonists were micromycetes of T. harzianum, T. lignorum, and T. longibrachiatum, which are also capable of exhibiting mycophilic properties (hyperparasitism). Thus, T. longibrachiatum showed mycophilia against three strains: F. moniliforme, F. moniliforme var annulatum, and F. oxysporum B3, whereas T. harzianum and T. lignorum did against two: F. moniliforme and F. proliferatum; the degree of phytopathogen inhibition (ID) varied from 30 to 100% (See Table 1). The strain of B. amiloliquefaciens bacterium was less active, the DI was 41.4%, on the average, and the slowest antagonistic properties were exhibited by actinobacterium S. lateritius - 14.8%, on the average. The investigation of the presence of the main hydrolytic enzymes (a hitinaze, a lipase, protease) showed that Trichoderma micromycetes had the average and strong hydrolytic activity (T harzianum and T. longibrachiatum), and bacteria (S. lateritius, B. amyloliquefaciens) had the average and weak hydrolytic activity (See Table 2). Also, all the investigated strains improved Scots pine seed germination, while the strains of B. amyloliquefaciens and T. longibrachiatum showed the greatest growth-promoting activity (See Figures). Thus, we found that the investigated strains (T harzianum, T. lignorum, T. longibrachiatum, S. lateritius, and B. amyloliquefaciens) had a high antagonistic activity, and Trichoderma micromycetes revealed the ability for mycoparasitism. The high biological (enzymatic, antagonistic, growth-stimulating) activity of the studied strains of microorganisms makes them effective agents for biological control in forest nurseries. The paper contains 2 Figures, 2 Tables and 24 References.

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