Nitrogenase activity (C2H2 reduction) of Azorhizobium in 2,4-D-induced root structures of wheat

The characteristics of C2H4 formation from C2H2 associated with 2,4-D-induced root structures on wheat seedlings inoculated with Azorhizobium caulinodans ORS571 have been investigated. Wheat seedlings treated with Azorhizobium plus 2,4-D were more tolerant in their C2H2 reduction activity to pO2 0.02 and 0.04 atm in the gas phase than wheat seedlings inoculated with Azorhizobium alone. C2H4 production was C2H2 dependent and was strongly inhibited by ammonia and nitrite. The nitrogenase activity of A. caulinodans associated with the 2,4-D-induced root structures of wheat seedlings was also confirmed by the fixation of 15N2.