Signals Released from Alfalfa Regulate Microbial Activities in the Rhizosphere

Abstract

The discovery that flavonoids from legumes induce transcription of nodulation (nod) genes in Rhizobium (Firmin et al 1986, Peters et al 1986, Redmond et al 1986) and Bradyrhizobium (Kosslak et al 1987) bacteria created new opportunities for soil microbiology. While initial work has centered on studies of how plant signals regulate microbial genes, future investigations will explore the ecological significance of microbial responses to plant signals. Both paths will increase our understanding of Rhizobium-legume associations, but agronomic applications may flow more rapidly from ecological studies that clarify how microbial responses change when plant signals are altered.