Bodiversity and antifungal properties of endophytes from the Madagascan medicinal plants Centella asiatica (L.)Urb. and Catharanthus roseus (L.) G. Don
(2012)
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- Abstract
- (en) In the recent years, endophytes from medicinal plants have attracted increasing attention. In particular, because they represent a rich source of new and useful compounds of pharmaceutical and agricultural interests and are a good niche for the discovery of novel microorganisms. Nowadays, very scanty information is available on endophytic microorganisms of the Madagascar flora. Although this island is rich of approximately 12000 plant species, of which more than 80% are endemic and potentially having medicinal virtues. The present work investigated the diversity and antifungal activities of microbial endophytes from two Madagascan medicinal plants, Centella asiatica (L.) Urb. and Catharanthus roseus (L.) G. Don. The study also outlined the interactions of some endophytic bacteria against Colletotrichum higginsianum, a causal agent of anthracnose disease on several plants, using in vitro-produced C. asiatica plantlets. Endophytes were isolated by microbiological methods following surface disinfection of plant tissues and plating onto appropriate culture media. The microorganisms were further identified using molecular tools. A new species of Colletotrichum, named Colletotrichum gigasporum sp. nov., from C. asiatica leaves and a new subspecies within the Streptomyces cinnamoneus group from C. roseus stems were described based on a combination of phenotypic properties and phylogenetic analysis. The sexual stage of C. gigasporum was obtained in laboratory cultures when the anamorph was plated onto culture media supplemented with sterilized leaf powder of C. asiatica. A number of beneficial endophytes were isolated from C. asiatica with biological control properties. In particular, Bacillus subtilis strain BCA31 was found to confer enhanced resistance to the in vitro plants of C. asiatica and significantly reduced disease incidence and severity caused by C. higginsianum. Also, the xylariaceous non sporulating species NSS1, the most frequently isolated fungal endophyte from C. asiatica leaves markedly inhibited the growth of C. higginsianum in dual culture experiments. Some of the isolated endophytes produced bioactive compounds which are of high interest to the pharmaceutical and agricultural sectors. In particular, Streptomyces cinnamoneus strain TS3RO was highly inhibitory against a large number of human and plant pathogenic fungi. Strain TS3RO is a good polyene macrolide antibiotic producer. Structural elucidation of the bioactive compound was obtained via LC/MS spectrometry, UV-visible spectra and NMR data. These findings provide additional insights on the high potential of endophytes from medicinal plants as a considerable source of new microbial species and useful bioactive compounds.
- Affiliations
UCLouvain SST/ELI/ELIM - Applied Microbiology
Citations
Rakotoniriana, E. F. S. D. (2012). Bodiversity and antifungal properties of endophytes from the Madagascan medicinal plants Centella asiatica (L.)Urb. and Catharanthus roseus (L.) G. Don. https://hdl.handle.net/2078.5/160320