Molecular analysis of botanical evidence by DNA thermal dissociation temperature

This work was based upon earlier studies which exploited indels located in the mitochondrial genome to discriminate between different varieties of grass. The nad7 and nad5 indels were amplified from the DNA of nine different varieties of amenity grass species typical of lawn and recreational use. Discrimination was achieved by differences in T _m values as shown by dissociation curve and supported by gel electrophoresis. Experiments were also implemented to determine the applicability of a genetic test using samples that were exposed to different environmental conditions. These were designed to include simulated conditions experienced by real forensic samples and consisted of grass leaves, stored dry inside paper envelopes at room temperature, desiccated grass leaves contaminated with fungal growth, and also stains made from grass leaves on cotton cloth to simulate grass marks that might be found on clothing. These stains were stored in a variety of conditions including, contact with soil, water logged, dry and exposed to sunlight and also stored dry in the dark and at 4°C for comparison. All samples except the soil and the fungus contaminated samples gave amplification products that could be distinguished by means of both gel electrophoresis and by T _m determined by a dissociation curve.