An expedient and versatile protocol for extracting high-quality DNA from plant leaves

INTRODUCTIONProtocols for extracting plant genomic DNA have to contend with two major challenges: preventing the oxidation of phenolic substances that can react with nucleic acids and proteins, and eliminating polysaccharides that interfere with downstream enzymatic manipulations of DNA. A protocol has been developed in which the above-mentioned substances are removed from the sample before the DNA is removed from the chromatin structure. This protocol requires only two tubes during extraction and a single precipitation step to yield high-quality DNA. DNA extracted with this method has virtually no protein or phenolic contaminants (A(260)/A(280)>1.8), is RNA-free, contains high-molecular-weight fragments according to CHEF electrophoresis, and is fully digestible by restriction enzymes. This protocol has been successfully tested with leaf samples from common bean and corn; with leaves known to be rich in phenolics (tomato and bell pepper), pectins (sweet orange, grapefruit, and peach), or both substances (Muscadine grape); and with leaves that contain latex in the sap (papaya).