Tissue grinding with ball bearings and vortex mixer for DNA extraction.

Many of the current applications of DNA technology require either the isolation of uncontaminated DNA from small tissue samples or the processing of a large number of samples. We are currently analyzing genetic variation in Panicum miliaceum L. and Manihot esculenta Christz by RAPD (Random Amplified Polymorphic DNA) (1). For RAPD analysis we require a technique that both quickly extracts DNA from a large number of accessions, and also minimizes the chance of contamination by extraneous DNA which could be amplified and give false results. Furthermore, in applications which analyze genetic variation in rare and endangered species, only small samples can be used. For example, in a current study of Asdepias medii Torr., an endangered species, existing plants are so small that removing a full leaf for DNA analysis would greatly compromise photosynthetic ability. We report here a simple, quick method of grinding plant tissue for DNA extraction. This procedure takes minutes per sample, yields finely ground leaf tissue, and minimizes the chance contamination by extraneous DNA because materials are used only once.