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Endophyte produces a variety of metabolites, which have antibiosis, anti-tumor activities and so on. The target of this study is plant endophytic fungus By254 preserved in our lab, isolated from the root of cotton, collected in 2006 from the suburb of Nantong, Jiangsu, China. We identified the strain By254 as Phomopsis sp. by morphological and molecular biological methods, then isolated and purified the fermentation products of strain By254.At last, three cytochalasins and twenty two fatty acids were isolated and identified. The content is as follows:First, the endophytic fungus By254 from cotton root was identified as Phomopsis sp.through morphological and molecular biological methods. The strain By254 was identified according to colony morphology on PDA and OMA, and conidial characteristics of cultures, which was reinforced by the internal transcribed spacer (ITS) region.Then, Phomopsis sp. By254 was fermented in solid state, and its metabolites were separated by chemical (column chromatography, thin layer chromatography and high performance liquid chromatography) and bioassay-guided fractionation. As a result, compounds 1,2,3 were afforded. They were identified as epoxycytochalasin H,cytochalasin N,cytochalasin H via ESI-MS (mass spectrum),1H-NMR,13C-NMR, DEPT135, HMQC, HMBC,1H-1HCOSY,NOESY.Antimicrobial activities of compounds 1,2,3 were further tested against 10 plant pathogenic fungi (Pythium ultimum, Fusarium graminearum, Sclerotinia sclerotiorum, Bipolaris maydis, Fusarium oxysporum, Phytopathora capsici, Botrytis cinerea, Bipolaris sorokiniana, Gaeumannomyces graminis var tritici, Rhizoctonia cerealis) and 10 plant pathogenic bacteria(Curtobacter luteum, Curtobacterium flaccumfaciens pv. flaccumfaciens, Acidovorax aveane subsp.citrulli, Clavibacter michiganensis subsp. sepedonicus, Clavibacter michiganensis subsp.michiganensis, Clavibacter michiganensis subsp. nebraskensis, Xanthomonas campestris pv. campestris, Xanthomonas campestris pv. oryzae, Rhodococcus fascians, Ralstonia solanacearum). As a result, all three compounds tested exhibited activity against nine pathogenic fungi except Phytopathora capsici, but no inhibition was observed against pathogenic bacteria. Moreover, the half maximal inhibitory concentration (IC50) of three compounds was tested by growth rate method. As a result, except compound 1 and 2 had weak activities against Pythium ultimum and Fusarium graminearum respectively, three compounds strongly inhibited growths of other pathogenic fungi, with IC50 value ranging from 0.15 to 57.32μg/mL.This is the first study to demonstrate antimicrobial activities of compounds 1,2,3 against tested plant pathogens.At last, we analyzed the compositions of volatile oil from Phomopsis sp. By254 for the first time. The oil was first extracted from strain By254 by organic solvent, transesterified in methanol and analyzed by GC-MS method. The results showed that twenty two compounds were identified from Phomopsis sp. By254, accounting for 93.0% of the total oil. The content of fatty acid was 92.6%,which mainly included Octadecanoic acid (18.7%),14-methyl-Pentadecanoic acid (16.3%),8, 11-Octadecadienoic acid (15.5%),Hexadecanoic acid (8.1%),11-Octadecenoic acid (7.2%).The content of unsaturated fatty acid was 41.6%.This is the first report on the compositions of volatile oil from Phomopsis sp.
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