Studies on relationship of rhizobial host specificity to growth of Acacia mangium, serological characteristics and nif gene
1997
Neelawan Pongsilp
Present study was aimed in identifying the effect of 21 isolates of fast-growing rhizobia (Rhizobium) and slow-growing rhizobia (Bradyrhizobium) host specific to the growth of 10 selected Acacia mangium families. Only Bradyrhizobium showed the positive response to the growth and biomass production of A. mangium. However, the same isolated Bradyrhizobium also affected differently to the growth and biomass production of different A. mangium families. This results indicated the rhizobial host specificity of A. mangium. Therefore, suitable Bradyrhizobium isolates were further applied to 10 A. mangium families. Based on the agglutination titer determination and Enzyme-Linked Immunosorbent Assay (ELISA), rhizobia used can be devided into 4 serogroups. Research on genotypic characteristics of rhizobial isolates were carried out by studying the plasmid profile. Rhizobium and Bradyrhizobium isolates have 1-3 large plasmids, ranging from 186-over 600 megadaltons. Hybridization method with the use of nifHDKE from Rhizobium japonicum as DNA probe against intact chromosome and plasmid DNA, the result showed that nif gene was detected only on Bradyrhizobium chromosome. No nif gene was observed in plasmid DNA of both Rhizobium and Bradyrhizobium. Study on hybridization to EcoRI and HindIII digests of total DNA to nif probe showed that serogroups and Restriction fragment length polymorphism (RFLP) patterns are correlated but differed from plasmid profile grouping.
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