Effect of Naringein and Quercetin on Activity of Nodabc Genes of Strain D293 and following Nodulation and Nitrogen Fixation Response of Inoculated Pea Plants (pisum Sativum L.)

Concentration and time course dependence of two structurally related plant flavonoids naringenin and quercetin on the nodABC gene transcriptional activity (as reporter gene nodC-lacZ activity) in Rh. leguminiosarum bv. vicae strain D923 and respective growth, nodulation and nitrogen fixing responses of plant host (garden pea) to inoculation with pre-induced strains were studied. Naringenin was more effective as a common nod genes inducer with maximum activity obtained at 0.5μÌ, while quercetin showed lower activity at a concentration of 15μÌ. According to the results quercetin was the better common nod genes-suppressor of Rh. leguminosarum bv viciae D293 growth. Incubation of germinating pea seeds with flavonoids–preactivated inocula (applied in effective concentrations), resulted in changed nodulation and nitrogen fixing patterns of plants after 35 days of growth. No direct relationship between common nod gene transcriptional activity of activated rhizobial inocula, following nodulation and nitrogen fixing response of plants was observed.