title: Isolation of Rhizobium meliloti nod Gene Inducers from Alfalfa Rhizosphere Soil.
abstract: Methanolic extracts of alfalfa rhizosphere soil induce more nod gene transcription in Rhizobium meliloti than extracts of nonrhizosphere soil. Six peaks of nod-inducing activity were separated by high-performance liquid chromatography from rhizosphere soil extract, and one compound was identified by H nuclear magnetic resonance, mass spectrometry, and UV-visible spectra as a formononetin-7-O-glycoside that activates both NodD1 and NodD2 proteins. The unanticipated presence of a glycoside in rhizosphere soil suggests either that large amounts of the glycoside were exuded by roots or that some glycosides are unexpectedly stable in soil.
authors.affiliation: Department of Agronomy and Range Science, University of California, Davis, California 95616.
authors.forename: M
authors.initials: M
authors.lastname: León-Barrios
authors.forename: F D
authors.initials: FD
authors.lastname: Dakora
authors.forename: C M
authors.initials: CM
authors.lastname: Joseph
authors.forename: D A
authors.initials: DA
authors.lastname: Phillips