Index >> Rhizobium and Legume Root Nodulation >>PCR Fingerprinting of DNA

These patterns are known to be stable and conserved even in clonal descendants of the same strain that had been propagated independently for some years. Therefore, patterns of DNA (fingerprints) are excellent tools for verification and identification of strains.

A present, DNA fingerprinting has been done on strains of rhizobia grown in pure culture and also on strains that were recovered from nodules induced by single strain inoculum in sterile media. The method has not been used to detect rhizobial strains in field conditions where multiple strains may be involved in producing different nodules on roots. The envisaged method involves collecting field grown plants or plants grown in sterilised medium inoculated with a known strain of Rhizobium and separating the nodules from roots. The nodules are surface sterilized followed by extraction of crude DNA. The polymerase chain reaction (PCR) is carried out to obtain amplified DNA fragments which are separated by gel electrophoresis on an acrylamide gel. The gels are stained and photographed to reveal patterns of DNA.