IDENTIFICATION AND CHARACTERIZATION OF FLAVONOIDS IN THE ROOT EXUDATEOF ROBINIA-PSEUDOACACIA

Eight compounds exuded from young roots of black locust (Robinia pseud oacacia) were separated by two-dimensional HPTLC, by HPLC and GC, and were identified by spectroscopic methods (ultraviolet/visible spectros copy and mass spectrometry) as 4',7-dihydroxyflavone, apigenin, naring enin, chrysoeriol and isoliquiritigenin. Structural assignments were c onfirmed by comparison with authentic standards. The capacity to induc e beta-galactosidase activity in Rhizobium sp. NGR234 containing a nod box::lacZ fusion on plasmid pA27 identified these flavonoids and the chalcone as nod gene inducers. This indicates the important role of th ese compounds in nodulation of this legume tree.