Protocol for isolation of genomic DNA from dry and fresh roots of medicinal plants suitable for RAPD and restriction digestion

Abstract

A simple and efficient protocol for isolating genomic DNA from fresh and dry roots of medicinal plants was developed. It involves a modified CTAB procedure using 3%CTAB, 4% b-mercaptoethanol, 2 M NaCl and 5% PVP. The extraction was carried out at 70°C. A slight increase in the concentrations of these chemical components and temperature helped in the removal of secondary metabolites and polysaccharides from the DNA preparation. The quantity and purity of isolated DNA was higher when compared with DNA extracted by the methods of Dellaporta et al. (1983) and Doyle and Doyle (1990). The DNA yield ranged from 33 to 68 µg per g of root samples and it was 1.47 times greater in dried than fresh samples. The DNA samples were found suitable for analysis with restriction enzyme digestion and random amplification of polymorphic DNA (RAPD). The total duration for DNA extraction from roots of medicinal plants using this protocol was 135 min as compared to 225 min with existing protocols. Key words: DNA isolation, roots, medicinal plants, secondary metabolite, PCR amplification, restriction digestion.