Potential inhibitors against Sclerotinia sclerotiorum, produced by the fungus Myrothecium sp. associated with the marine sponge Axinella sp.

Abstract

Sclerotinia sclerotiorum is a worldwide ascomycete fungal plant pathogen, which causes enormous yield losses on major economic crops such as crucifers, grain legumes and several other plant families. The objective of this research was to isolate and characterise some bioactive products from cultures of fungi associated with the marine sponge Axinella sp. In total, nine fungal isolates were obtained from the marine sponge Axinella sp. collected from the South China Sea. A group of test strains, including two G + strains (Bacillus subtilis and Staphylococcus aureus), two G − strains (Escherichia coli and Pseudomonas aeruginosa) and three fungi including two plant pathogenic fungi Sclerotinia sclerotiorum and Magnaporthe grisea and Saccharomyces cerevisiae, were employed as the indicator organisms for bioactivity screening. Using antagonistic tests and bioactive screening of the ethyl acetate (EtOAc) extracts of the corresponding cultures, fungal isolate JS9 showed the stronger efficacy against the test indicator strains, especially the indicator fungal pathogens. Isolate JS9 was further identified as Myrothecium sp. by a combination of morphological features and 18S rDNA BLAST on GenBank. Two macrocyclic trichothecenes, roridin A (compound 1) and roridin D (compound 2) were purified by tracking the activity of the EtOAc extract fractions and characterised with spectral analyses including MS, 1 H-NMR, 13 C-NMR and disortionless enhancement by polarization transfer (DEPT). In vitro antifungal tests showed that the two macrocyclic trichothecenes were bioactive against S. cerevisiae, M. grisea and S. sclerotiorum with minimal inhibitory concentrations of 31.25, 125 and 31.25 μg ml −1 for roridin A, and 62.5, 250 and 31.25 μg ml −1 for roridin D, respectively. The present investigation demonstrated that two antifungal trichothecenes including roridin A and roridin D produced by the fungus Myrothecium sp. isolated from the marine sponge Axinella sp. could be potential inhibitors against the plant pathogen S. sclerotiorum.

Botryane Sesquiterpenoids, Cyclopentadepsipeptides, Xanthones, and Trichothecenes from Trichoderma oligosporum

“…Trichothecenes (16)(17)(18)(19) have been recorded as important food mycotoxins that can cause serious harm to skin and mucosa [36]. Considering the high content of trichothecenes produced by this fungus, T. oligosporum should be seen as a potential mycotoxigenic fungus in food or feed.…”

First report of Myrothecium roridum from a gymnosperm. North American Fungi

“…Since M. roridum produces two trichothecenes that significantly affect the rice blast pathogen (Wang et al 2007) and another Myrothecium sp. produces inhibitors that are effective against S. sclerotiorum (Xie et al 2008), it is at least possible that M. roridum will aid whitebark pine restoration at CLNP by acting against white pine blister rust. Further research is necessary.…”

“…can produce biologically active trichothecenes that can potentially work against pathogens such as the rice blast fungus, Pyricularia oryzae Cavara (Wang et al 2007), and Sclerotinia sclerotiorum (Lib.) de Bary (Xie et al 2008). Myrothecium roridum has been described as plurivorous (Fitton and Holiday 1970), and although a total of 263 fungus-host records include 119 host genera, all reported hosts are Angiosperms (Farr et al 2009).…”

Marine-Derived Fungi: A Promising Source of Halo Tolerant Biological Control Agents against Plant Pathogenic Fungi

“…This result is in accordance with a previous study which reported that crude ethyl acetate extract of Myrothecium sp. associated with the marine sponge, Axinella sp., was a potential producer of antifungal compounds against Sclerotinia sclerotiorum, a causal agent of stem rot in various crops 41 . Meanwhile, the crude extracts of three Emericella species including E. nidulans, E. rugulosa and E. variecolor showed high inhibition of the mycelial growth of eight of the tested plant pathogenic fungi at 1 g/L.…”