HOST-SPECIFIC REGULATION OF NODULATION ME DIATED BY FLAVONOID COMPOUNDS PRESENT IN PLANT

Induction by Rhizobium bacteria of symbiotic nitrogen-fixing root nodu les on legume plants is a host-specific process. The use of a reporter gene, whose transcription can be detected easily by assaying for beta -galactosidase activity allowed quickly description of inducers in see d extracts and root exudates of various legumes. The transcription of nodulation (nea) genes in the symbiotic bacteria is induced by particu lar flavonoid signals, mainly flavones and isoflavones. The amounts, t he diversity and the activity of the flavonoids interacting with produ cts from nodD genes determine specificity and intensity of the nodulat ion. Flavonoids are molecules active at low concentrations and their t echnological use open new field to control plant-microbe interactions in the rhizosphere.