The identification of strains of rhizobia has been made by host specificity and regular microbiological tests. By forming a phylogenetically heterogeneous group, different molecular techniques have been employed to assist in the genetic characterization and identification of efficient and competitive strains for production of inoculants. This study aimed to characterize the spacer region 16S-23S rDNA of the strains of rhizobia used in commercial inoculants in Brazil for legume species, using PCR combined with RFLP, and assess the possibility of using this molecular marker as an auxiliary method for identification of strains. The amplification of the 16-23 S rDNA spacer region of rhizobium strains generated fragments with sizes ranging between 700 and 1350bp. Products from the amplification were subjected to digestion with Mps I, Dde I and Hae III endonucleases. The results indicated the possibility of using the technique of PCR-RFLP of 16S-23S spacer region rDNA as molecular marker to differentiate most strains tested and recommended for production of inoculants, in addition to the traditional microbiological techniques. However, this marker is not sufficiently discriminatory to be used in the identification of the strains recommended for the production of commercial inoculants.
quality of inoculants; PCR-RFLP; molecular markers
