Project description:<p><strong>BACKGROUND:</strong> The coevolution and interaction between plants and microorganisms have long been a subject of significant research interest. Dark septate endophytes (DSE) have garnered great attention in contemporary research due to their functional diversity, in vitro cultivation ability, and ability to establish symbiotic associations with host plants. In the present study, three DSE strains, namely <em>Acrocalymma vagum</em>, <em>Zopfiella marina</em>, and <em>Phoma herbarum</em>, which were obtained from the roots of <em>Astragalus membranaceus</em>, were introduced into maize plants through inoculation. We evaluated the effects of DSE inoculation on maize growth and root secretion activity through a multi omics methods, and proposed mechanisms for 'internal pathways' and 'external pathways'.</p><p><strong>RESULTS:</strong> The findings indicated that A. vagum exhibited superior growth-promoting ability on maize compared to <em>Z. marina</em> and <em>P. herbarum</em>.GO and KEGG enrichment analysis found that <em>A. vagum</em> inoculation resulted in significant enrichment of differentially expressed genes in annotation functions related to hormone regulation and lipid metabolism. A. vagum inoculation revealed that the gene pathways involved in plant hormone signaling and plant pathogen interactions play a crucial role in promoting host growth, and <em>A. vagum</em> inoculation group exhibited the highest number of differentially expressed genes, the most intricate protein-protein interaction (PPI) model, and the most pronounced relationship between differentially expressed genes. After the inoculation of <em>A.vagum</em>, the levels of salicylic acid, zeatin, and IAA in maize plants significantly increased. Additionally, the diversity and abundance of endophytic fungi, as well as the proportion of harmful bacteria and beneficial fungi, had significantly increased. Compared with <em>Z. marina</em> and <em>P. herbarum</em>, the net photosynthetic rate (Pn) and stomatal conductance (Gs) of <em>A.vagum</em> inoculated plants significantly increased. Inoculation with <em>A.vagum</em> could enhance the ability of corn roots to secrete lipids, sugars, and amino acids, resulted in a notable augmentation of beneficial bacteria and fungi, accompanied by a significant reduction in the proportion of harmful bacteria in the rhizosphere soil, such as <em>Fusarium solani</em> and <em>Fusarium lacertarum</em>, exhibited significant inhibition, whereas <em>Bacillus niabensis</em> and <em>Bacillus nealsonii</em> demonstrated enrichment trends. Soil pH, organic matter, available potassium content, acid phosphatase, alkaline phosphatase and urease activity exhibited significant increases following the inoculation of <em>A. vagum</em>. Variance decomposition and structural equation modeling (SEM) analysis indicated that the 'internal pathway', maize growth is mainly influenced by the interaction of endogenous hormones, endophytic microorganisms, and photosynthetic parameters, whereas within the 'external pathway', the interaction between soil microorganisms and soil physicochemical properties exerted a dominant influence. Compared with the <em>Z. marina</em> and <em>P. herbarum</em> inoculation, <em>A. vagum</em> inoculation showed a more significant impact on maize growth, both in terms of 'internal pathway' and 'external pathway', in terms of pathway level and quantity.</p><p><strong>CONCLUSIONS:</strong> These findings provide a new perspective for understanding the potential mechanisms of 'microbe-plant' interactions and also contribute to the exploration of targeted functional microorganisms that promote growth and stress resistance.</p>
Project description:Rhizopycnis acids A (1) and B (2), two new anisic acid derivatives, were obtained from the ethyl acetate extract of the fermentation cultures of Rhizopycnis vagum, an endophytic fungus isolated from the healthy tissues of Nicotiana tabacum. The structures of the two compounds were determined through a series of 1D and 2D NMR and HRMS spectral analyses. Both compounds were the first anisic acid derivatives containing methylbutanoic/methylbutenoic acid group found in fungi. 1 and 2 displayed antibacterial activity against six tested bacteria with IC50 values in the range 16.1~81.3 μg/mL.
Project description:Rhizovagine A (1), a novel dibenzo-α-pyrone alkaloid with an unprecedented 5/5/6/6/6 fused pentacyclic skeleton, was isolated from the endophytic fungus Rhizopycnis vagum Nitaf22. The structure was elucidated by comprehensive spectroscopic analysis, in combination with quantum chemical 13C NMR and electronic circular dichroism (ECD) calculations for configurational assignment. A plausible biosynthetic pathway for 1 was proposed. Compound 1 displayed acetylcholinesterase inhibitory activity.
Project description:Fourteen new eremophilane-type sesquiterpenoids, named rhizoperemophilanes A~N (1~14), together with eight known congeners, were isolated from the culture of the endophytic fungus Rhizopycnis vagum. The structures of the new compounds were elucidated by extensive spectroscopic analyses, as well as ECD calculations and the modified Mosher's method for the assignment of the absolute configurations. Rhizoperemophilane J (10) contains an uncommon C-4/C-11 epoxy ring, while rhizoperemophilane N (14) features an unprecedented 3-nor-eremophilane lactone-lactam skeleton. These metabolites were evaluated for their antibacterial, cytotoxic, and phytotoxic activities. Among them, compounds 11, 16, and 20 displayed antibacterial activities, while 14 showed selective cytotoxicity against NCI-H1650 and BGC823 tumor cells. Moreover, compounds 5, 6, 12, 13, 16, and 19 exhibited strong phytotoxic activities against the radicle elongation of rice seedlings.