Intraspecific variation in the internal transcribed spacer (ITS) regions of rDNA in Withania somnifera (Linn.) Dunal

Intraspecific variation in ITS regions of the rDNA among the five wild and five cultivated genotypes of Withania somnifera, were evaluated at nucleotide sequence level using restriction fragment length polymorphism (RFLP). The entire internal transcribed spacer (ITS1-5.8S-ITS2) region was first amplified by PCR and then cleaved with four different restriction enzymes (EcoRV, Hinf I, Afa I & Hae III). Restriction endonuclease digests, types, and sequence length composition of ITS 1 and ITS 2 of nuclear ribosomal DNA provided discrete differences between the cultivated and wild genotypes. A 710 bp single amplified product was obtained in all the five wild genotypes whereas, two ITS bands named as ITS type A and B of 709 bp and 552 bp, respectively were obtained in the five cultivated genotypes. A single deletion at 672 position was noted in ITS type A of cultivated genotypes. There was no restriction site in 552 bp ITS band for all the four restriction enzymes used. The variation of ITS at amplification as well as digestion level is in conformity with morphological and phytochemical differences in W. somnifera genotypes.