Measuring DNA damage in higher plants is important in assessing the impacts of environmental conditions, e.g., increased UV resulting from ozone depletion, and in testing the relationship of productivity to DNA damage and repair. Sunlight exposure of plants produces UV-induced DNA damages measurable by treating DNA with damage-specific enzymes and dispersion of DNA molecules in denaturing media. Such DNA must he enzyme-digestible, with few single strand breaks. DNA isolation must preclude repair, providing a "snapshot" of DNA damage. We developed a method for isolating DNA from several crop plants, both monocots and dicots - alfalfa (Medicago sativa L.), pea (Pisum sativum L.), rice (Oryza sativa L.), soybean [Glycine max (L.) Merr.], sorghum [Sorghum bicolor (L.) Moench], and spinach (Spinacia oleraceae L.). This method is simple, readily deals with multiple samples, and avoids organic solvents. We show that pyrimidine dimers can readily be quantified in DNA prepared by this method. This method should also be useful for other experiments requiring high molecular length, enzymatically digestible plant DNA.
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