Intraspecific variation in the internal transcribed spacer (ITS) regions of rDNA in <i style="">Withania somnifera</i> (Linn.) Dunal

325-328Intraspecific 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 &amp; 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

Utility of multidisciplinary approach for genome diagnostics of cultivated and wild germplasm resources of medicinal Withania somnifera, and status of new species, W. ashwagandha, to the cultivated taxon

Realizing the inconsistencies that exist in the extent and nature of differentiation in the Withania somnifera genetic resources in India, the 21 cultivated and wild accessions, and the two hybrids (cultivated 9 wild accessions and vice versa) were investigated for morphological,cytogenetical, chemical profiling, and crossability features.Their nuclear and chloroplast genomes were also assayed at the nucleotide sequence level, and by use of DNA markers. Chloroplast DNA diversity and somatic chromosome number (2n = 48) were not helpful in identifying the differences. Other approaches, on the other hand, especially restriction endonuclease digests, types and sequence length composition of ITS 1 and ITS 2 of nuclear ribosomal DNA, AFLP fingerprinting, and crossability barriers unambiguously provided startling discrete differences between the cultivated and wild accessions, indicating a clear division of W. somnifera into two distinct lineages.These data, therefore, are indicative of the fact that because of the unique characteristics of its nuclear genome, and strong crossability barriers vis-a`-vis wild accessions of W. somnifera, the cultivated accessions should be relegated to the rank of the separate species, W. ashwagandha