Ribosomal DNA sequence analysis of different geographically distributed aloe vera plants: comparison with clonally regenerated plants

ABSTRACT

A comparison of the sequences in an internally transcribed spacer [ITS] 1 region of rDNA between clonally regenerated A. vera and the same species in Japan, USA and Egypt revealed the presence of two types of nucleotide sequences, 252 and 254 bps. Based on the findings in the ITS 1 region, A.vera having 252 and 254 bps clearly showed a stable sequence similarity, suggesting high conservation of the base peak sequence in the ITS 1 region. However, frequent base substitutions in the 252 bps sample leaves that came from callus tissue and micropropagated plants were observed around the regions of nucleotide positions 66, 99 and 199-201.The minor deviation in clonally regenerated A.vera may be due to the stage of regeneration and cell specification in cases of the callus tissue. In the present study, the base peak sequence of the ITS 1 region of rDNA was adopted as a molecular marker for differentiating A.vera plants from geographically distributed and clonally regenerated A.vera plants, and it was suggested that the base peak substitutions in the ITS 1 region may arise from the different nutritional and environmental factors in cultivation and plant growth stages