Isolation of Genomic Dna from Five Species of Euphorbiaceae without Liquid Nitrogen

The isolation of intact, high-molecular mass genomic DNA is essential for many molecular biology applications including PCR, endonuclease digestion, southern blot analysis, and genomic library construction. Many protocols are available for the extraction of genomic DNA from plant tissue, and all the protocols have used expensive and hazardous chemical-liquid nitrogen for grinding plant material or DNA isolation kits for extraction. In the present study a modified CTAB (Cetyl trimethyl ammonium bromide) method has been used for isolation of genomic DNA from the leaves of five species of Euphorbiaceae viz., Ricinus communis, Excoecaria robusta, Hevea brasiliensis, Jatropha multifida and Jatropha curcas. Key step in the modified CTAB method is the use of alcohol for submerging leaf tissue instead of grinding it in liquid nitrogen. The protocol described (alcohol fixation) has yielded genomic DNA with excellent quality, which is comparable to those results of liquid nitrogen ground leaves. The genomic DNA isolated has an excellent absorbance (A260/A280) ratio observed between 1.80 and 2.00, indicating good genomic DNA without contaminants, highly suitable for PCR amplification.