Abstract

DNA extraction in many plants is difficult because of metabolites that interfere with DNA isolation procedures and subsequent applications, such as DNA restriction, amplification and cloning. We have developed a reliable and efficient method for isolating genomic DNA free from polysaccharide, polyphenols and protein contaminants from tropical tuber crops (Elephant foot yam, Cassava, Sweet potato Taro and Tannia). The method involves inactivation of contaminant proteins by using CTAB/Proteinase K and precipitation of polysaccharides in the presence of high concentration of salt. The purity of genomic DNA was confirmed by A_260/280 and A_260/230 ratios calculated from the spectrophotometric readings and further by restriction analysis of the isolated DNA using restriction enzymesEcoRI and Hind III. The described protocol also resulted in the isolation of sufficiently higher yield of DNA from leaf sample of tropical tuber crops. The new protocol can be successfully used for both small and large scale preparation of genomic DNA from leaf tissues of tuber crops which is highly suitable for further down stream processes like PCR amplification and restriction digestion analysis.

Key words: DNA isolation, RAPD, restriction enzyme digestion, tuber crops.

Abbreviation

 CTAB, Cetyltrimethylammonium bromide; EDTA, hexadecyltri-methylammoniumbromide; PVPP, polyvinylpolypyrrolidone; PEG, polyethylene glycol; RAPD, randomly amplification of polymorphic DNA.