Species-Specificity of an Elicitor-Active Oligosaccharide, LN-3, to Leguminous Plants

Abstract

Abstract LN-3, a linear pyridylaminated hepta-β-glucoside previously found to show elicitor activity in alfalfa cotyledons, was examined for phytoalexin-inducing activity in pea epicotyl and bean cotyledon assays. LN-3 did not show (+)-pisatin-inducing activity in pea epicotyls. In the bean cotyledon assay, however, the (± )-kievitone content gradually increased with increasing LN- 3 concentration, and reached a maxim um (ca. 17 |ig/g fresh wt) at 100 μ/ml. Half-maximal elicitor activity was seen at ca. 16 μm . After three legumes, alfalfa, pea and bean, were treated with LN-3, the recovery of the rem aining LN-3 or its fragments was examined. Almost 100% of LN-3 or its fragments was recovered from the pea test solution; in contrast, recoveries from alfalfa and bean were only 63.8 and 38.1% , respectively. HPLC and LC-MS analyses of the recovered samples indicated that LN-3 was hydrolyzed to give mono- and/or diglucoside( s) in the alfalfa and the bean solutions, while in the pea experiment a small portion of LN-3 was hydrolyzed to give sugar fragments with different degrees of polymerization < 7.