Characterisation of the Saponin Hydrolysing Enzyme Avenacoside- -l-rhamnosidase from the fungal pathogen of cereals, Stagonospora avenae

The fungal pathogen Stagonospora avenae f. sp. avenaria infects oat leaves, which contain the saponins avenacoside A and B. The avenacosides are glycosylated steroidal saponins that occur within oat leaves in a non-fungitoxic form and are converted upon damage or pathogen invasion to their antifunga...

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Bibliographic Details
Published in:European journal of plant pathology 2004-04, Vol.110 (4), p.421-427
Main Authors: Bleddyn Hughes, H., Morrissey, John P., Osbourn, Anne E.
Format: Article
Language:English
Subjects:
Fungi
Leaves
Pathogens
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Summary:The fungal pathogen Stagonospora avenae f. sp. avenaria infects oat leaves, which contain the saponins avenacoside A and B. The avenacosides are glycosylated steroidal saponins that occur within oat leaves in a non-fungitoxic form and are converted upon damage or pathogen invasion to their antifungal form by a plant enzyme. It has previously been shown that oat-attacking isolates of S. avenae are able to hydrolyse the sugar chain at the C3 position of the avenacosides. This carbohydrate moiety is a branched chain that consists of one α-{scL}-rhamnose and two or three β-{scD}-glucose residues in avenacosides A and B, respectively. Removal of the α-{scL}-rhamnose residue is sufficient to detoxify the avenacosides. This work describes the purification of the avenacoside-degrading α-{scL}-rhamnosidase-and determination of peptide sequence from the protein which represents the first α-{scL}-rhamnosidase thus characterised in a fungal plant pathogen.[PUBLICATION ABSTRACT]
ISSN:0929-1873
1573-8469
DOI:10.1023/B:EJPP.0000021083.94707.1e