Molecular characterization of Steinernema thermophilum based on RFLP and sequence of ITS region of rDNA

Restriction Fragment Length Polymorphism (RFLP) profiles of the amplified products of Internal Transcribed Spacer (ITS) region of rDNA using four restriction enzymes (AluI, RsaI, HinfI and HhaI) revealed distinctness of Steinernema thermophilum from other two Indian isolates of Steinernema (IARI-EPN-ut1and IARI-EPN-mg1). One of the restriction enzyme, Alu I could differentiate all the three species/strains from one another. The base sequence of ITS region of ribosomal DNA of S. thermophilum exhibited maximum similarity with S. abbasi (96.95%), followed by S. ceratophorum (80.56%), S. bicornutum (80.42%) and S. riobrave (79.94%), from which it could be further differentiated by characteristic sequence of their ITS regions, including sequence lengths and composition, and differences in base characters in sequence alignment. The base sequence (1–667 bp) of S. thermophilum has been deposited in Genbank under the accession number: DQ 665651.