Simple method of genomic DNA extraction from Rhizobia in dried nodules of Phaseolus vulgaris for strain differentiation by PCR-based DNA fingerprinting

Repetitive DNA PCR fingerprinting of bacterial genomic DNA is a useful tool for typing and differentiation of rhizobial strains. The method was report ed to be suitable for strain differentiation of Rhizobia present in individ ual root nodules of some leguminous plants without the need for isolation a nd cultivation of the strains, in which rhizobial genomic DNA was extracted directly from each fresh or frozen nodule, We developed a new protocol of rhizobial genomic DNA extraction/purification from dried nodules of Phaseol us vulgaris for generating repetitive DNA PCR fingerprints of Rhizobia pres ent in the nodules, The simplified protocol consists of only three major st eps, heat extraction of genomic DNA from rhizobial cells prepared from drie d nodules, ethanol precipitation of the DNA and Sephadex G-50 column purifi cation of the DNA, and generated fingerprints with good quality for differe ntiation of Rhizobia strains. The protocol will be useful to examine the no dule occupancy of inoculated rhizobial strains in field experiments.