title: Presence of trifoliin A, a Rhizobium-binding lectin, in clover root exudate.
abstract: Trifoliin A, a Rhizobium-binding glycoprotein from white clover, was detected in sterile clover root exudate by a sensitive immunofluorescence assay employing encapsulated cells of Rhizobium trifolii 0403 heat-fixed to microscope slides. Its presence in root exudate was further examined by immunoaffinity chromatography. The binding of trifoliin A to cells was specifically inhibited by the hapten, 2-deoxyglucose. Significantly higher quantities of trifoliin A were detected in root exudate of seedlings grown hydroponically in nitrogen-free medium than in rooting medium containing 15 mM NO-3, a concentration which completely suppressed root hair infection by the nitrogen-fixing symbiont. The presence of trifoliin A in root exudate may make it possible for recognition processes to occur before the microsymbiont attaches to its plant host.
mesh_terms: D002846:Chromatography, Affinity; D005419:Flavonoids / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D037102:Lectins / Q000032:analysis*; D037121:Plant Lectins; D010944:Plants / Q000276:immunology*; D011794:Quercetin / Q000031:analogs & derivatives / Q000032:analysis*; D012231:Rhizobium / Q000276:immunology*
chemical_list: D005419:Flavonoids; D037102:Lectins; D037121:Plant Lectins; C016527:isoquercitrin; D011794:Quercetin