Specific binding of a fungal glucan phytoalexin elicitor to membrane fractions from soybean Glycine max
Treatment of soybean tissues with elicitors results in the production of phytoalexins, one of a number of inducible plant defense reactions against microbial infections. The present study uses a ..beta..-1,3-(/sup 3/H) glucan elicitor fraction from Phytophthora megasperma f.sp. glycinea, a fungal pathogen of soybean, to identify putative elicitor targets in soybean tissues. Use of the radiolabeled elicitor disclosed saturable high-affinity elicitor binding site(s) in membrane fractions of soybean roots. Highest binding activity is associated with a plasma membrane-enriched fraction. The apparent K/sub d/ value for ..beta..-glucan elicitor binding is approx. = 0.2 x 10/sup -6/ M and the maximum number of binding sites is 0.5 pmol per mg of protein. Competition studies the (/sup 3/H)glucan elicitor and a number of polysaccharides demonstrate that only polysaccharides of a branched ..beta..-glucan type effectively displace the radiolabeled ligand from membrane binding. Differential displacing activity of the glucans on P. megasperma elicitor binding corresponds closely to their respective ability to elicit phytoalexin production in a cotyledon bioassay.
- Research Organization:
- Universitaet Freiburg, Germany, F.R.
- OSTI ID:
- 5354025
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 84:12; ISSN PNASA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
BACTERIA
BIOCHEMICAL REACTION KINETICS
CARBOHYDRATES
DISEASES
FUNGAL DISEASES
FUNGI
GLYCINE HISPIDA
INFECTIOUS DISEASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEGUMINOSAE
MEMBRANE PROTEINS
MICROORGANISMS
ORGANIC COMPOUNDS
PLANTS
POLYSACCHARIDES
PROTEINS
RADIORECEPTOR ASSAY
REACTION KINETICS
RECEPTORS
RHIZOBIUM
SACCHARIDES
TRACER TECHNIQUES
TRITIUM COMPOUNDS