Rice root on putting soil receiving urea N-fertilizer  and inoculated with Rhizobium leguminosarum bv. trifolii strain E11
Ten ng of each DNA sample were used as template in PCR with the following final concentrations of reagents: 400 nM 563F (forward) primer, 400 nM 924R (reverse) primer, 1X FastStart High Fidelity PCR Buffer (Roche, Cat # 03 553 400 001), 0.5 U of Taq polymerase (Roche), 200 mM dNTPs. Each reaction was set up in triplicate and amplified using the following cycle: 94 C/3 min, followed by 30 cycles at 94 C/45 sec, 56 C/45 sec, and 72 C/1 min, and a final extension at 72 C/7 min.