The dissertation is related to study of biological (phytotoxical, antibacterial and antifungal) activities of endophytic UСМ F-16795 and saprotrophic UСМ F-16790 Penicillium funiculosum strains, synthesis of cellulase and xylanase enzyme complex, phytohormonal compounds and influence of endophytic and saprotrophic strains on soybean (Glycine max L.) under salt stress.
Endophytic fungi P. funiculosum were isolated from plants of Ukrainian Polissya. Ten endophytic strains were dominant, i.e. occurred in plants with a high frequency (59%). Saprotrophic strains were obtained from Ukrainiana collection of microorganism. Studied strains were identified on the base of culture and morphological characteristics. For molecular genetic identification of studied P. funiculosum strains, endophytic UСМ F-16795 and saprotrophic UСМ F-16790 strains were selected which had the highest physiological activity. According to ITS region rDNA sequences, the selected strains are identified as Talaromyces funiculosus (Thom) Samson, Yilmaz, Frisvad & Seifert (anamorph Penicillium funiculosum Thom). Based on the 100% mutual homology of the ITS region rDNA sequences of studied strains and 99.45% cross-homology with type cultures Penicillium funiculosum ATCC 8725 (HQ026723) and Talaromyces funiculosus CBS 272.86 (NR_103678) endophytic UСМ F-16795 and saprotroph UСМ F-16790 strains were registered in GenBank by the numbers KY620212 and KY865175, respectively. P. funiculosum strains from different ecological niches demonstrated antagonistic activity against plant pathogenic bacteria of Agrobacterium and Pseudomonas genera. Endophytes had selective antibacterial activity against pathogenic bacteria, the growth inhibition zones were 15-35 mm. All saprotrophic strains inhibited growth of test cultures, the growth inhibition zones were 13-45 mm. The absence of antifungal activity of all investigated P. funiculosum strains against three yeast and eight plant pathogenic fungi was shown. For the first time, the absence of phytotoxicity of endophytic P. funiculosum strains was shown, whereas phytotoxicity of all saprotrophic isolates reached 30-75% by dry biomass weight of corn shoots and roots. Two saprotrophic strains UСМ F-16825 and UСМ F-16794 showed phytotoxic activity against Chlorella vulgaris and C. kessleri strains. Enzymatic index (EI) for cellulase of the endophytes (80%) was moderate (ЕІ=1.22-1.49), and 30% saprotroph – low, 40% – moderate and 30% – high (ЕІ=1.11-2.0). EI for xylanase of 70% endophytic strains was low (1.11-1.82), whereas for saprotrophic ones – only high (1.56-2.16). For the first time synthesis induction and dynamics of cellulase and xylanase enzyme complex of endophytic P. funiculosum strains was studied. It was established that the natural substrate wheat straw is the better inducer of synthesis of cellulase enzyme complex and xylanase than Na-CMC. HPLC/MS analysis showed that endophyte and saprotroph P. funiculosum synthesized gibberellins: GA3 (6.8 and 4.1 ng/g dw, respectively), GA4 (4.9 and 11.6 ng/g dw) and trace amounts of GA7. The total level of auxin synthesis did not significant difference between endophytic and saprotrophic P. funiculosum strains (6.24 ± 0.49 and 6.61 ± 0.52 μg/ml, respectively). However, endophytic strain synthesized 4.00 ± 0.24 μg/ml physiologically active indole-3-acetic acid (IAA), which is 55% more compared to saprotroph. Notably, endophytic strain synthesized 2.2 times higher total amount of cytokines (30.21 ± 2.42 μg/ml) than saprotroph. Saprotrophic strain produced 20% higher level of the transport form of cytokines – zeatin riboside (3.60 ± 0.17 μg/ml). Endophytic P. funiculosum strain synthesized 76% (3.97 ± 0.25 μg/ml) higher level phytohormones of antistress and inhibitory action – abscisic acid (ABA) compared to saprotroph. For the first time comparative effects of endophytic and saprotrophic P. funiculosum strain on soybean under salt stress condition was studied. It has been shown that the endophytic UСМ F-16795 P. funiculosum strain contributed to overcoming salt stress by soybean and biomass accumulation of plants on the model system "plant-micromycetes". In contrast saprotrophic one did not effect on plant resistance under this stress factor. Thus, complex of biological activities of endophytic and saprotrophic P. funiculosum strains that synthesise metabolites with antibiotic, enzymatic, phytostimulating actions was studied for the first time. Studied P. funiculosum strains from different ecological niches are identical by cultural and morphological, molecular and genetic characteristics; they synthesize the same complex and different amount of biologically active compounds, which causes the formation different relationships with plants (mutualist or saprobiont), which is clearly showed by the effect of salt stress.
