Using Reporter Gene System to Monitor Applied Bradyrhizobium in Thailand

To distinguish applied strain of Bradyrhizobium japonicum and Bradyrhizobium spp. From other indigeneous strains in soil samples, the development of marker gene has been achieved. Bradyrhizobium spp. strain TAL 1000 for Arachis hypogaea and B. japonicum strain TAL 379 for Glycine max were used as recepient strain for introduction GUS transposon. E. coli strain S17-1 lambda pir/pUt mTn5SS gus A31 was used as a donor strain. After applied both of conjugant strains to the host plant of origin, the nodule formation and plant growth were observed. The result of plant growth was found no statistically different among applied gus+ and wild type strain. To determine nodule occupancy, 106 cell of both gus+ strains were inoculated to seeds in sterlied sand as control and five sandy soil samples after 27 days of plant growth, the nodules were stained to detect bule nodules. The competition behavior data between applied and soil indigencous strain was implied from the percent of nodule occupancy. The range of competition is in the degree 14–60%. From this system studied here could be developed for buid up the better croping management for farmers who interested to plant such as Soy-bean, Peanut and Mungbean with rhizobial inocula commercial strains.