[Genetic diversity of peanut bradyrhizobia estimated by culture-independent vs. culture-dependent approaches].

OBJECTIVE

To develop a rapid technique for estimating the percentage of bradyrhizobial nodule occupancy, we comparaed the differences of genetic diversity of peanut bradyrhizobia with culture-independent and culture-dependent methods.

METHODS

We used the traditional media plate technique for isolation of peanut bradyrhizobia and directly collected the bacteroids from peanut nodules. The BOX-PCR fingerprintings were compared after amplification with the DNAs of peanut bradyrhizobial isolates by culture-dependent approach and bacteroids by culture-independent approach.

RESULTS

The percentage of testing for peanut bacteroids was 81.8% with culture-independent method, and 85 genotypes of BOX-PCR were obtained. The percentage of isolation for peanut bradyrhizobia strains was 72.7% and 71 genotypes of BOX-PCR were produced. There were totally 17 corresponding BOX-PCR genotypes obtained by both methods.

CONCLUSION

The culture independent method for direct analysis of genetic diversity from bacteroids in nodules can much more rapidly and clearly find the dominant genetic groups in different soil samples and fast figure out the.percent of the rhizobia nodule occupancy.