Evaluation of plant seed DNA and botanical evidence for potential forensic applications

Seeds, the reproductive organs of plants, are common as trace evidence from crime scenes. Seed evidence could be grouped into several categories based on the types of crimes they are associated with, including child abuse, homicides and drugs. Most commonly, seeds are examined microscopically and identified to the plant species level to show a linkage between persons and places. More recently, forensic researchers have evaluated the potential for extracting and typing DNA from seeds to further individualize the samples. As a model system, tomato seeds were examined microscopically after different cooking treatments and assessed for the potential to DNA type seeds for variety identification. A sufficient quantity and quality of DNA were recovered from uncooked, digested and undigested tomato seeds for amplified fragment length polymorphism (AFLP) analysis; however, any form of cooking destroyed the seed DNA. A simple microscopic analysis was able to distinguish between a cooked tomato seed versus an uncooked seed. This article is intended to provide an overview of case examples and current techniques for the forensic examination of seeds as plant-derived evidence.