DNA Analysis of Ingested Tomato and Pepper Seeds

Abstract

Ingested food is one of the important types of forensic evidence obtained during a medicolegal autopsy. Many materials containing seeds pass through the human digestive system and are still recognizable; thus, they can be valuable for providing investigative leads. Currently, the identification of seeds relies on microscopic and morphologic examination. However this method sometimes can be problematic. For example, the microscopic appearance of the ingested tomato and pepper seeds is very similar; thus, it is not always easy to distinguish these seeds by comparing their physical characteristics. Tomato and pepper seeds were selected as a model system to assess the value of performing DNA analysis as an alternate and/or complimentary means of seed identification. Results of blind testing indicate that the deoxyribonucleic acid-amplified fragment length polymorphism (DNA-AFLP) results were able to discriminate between pepper and tomato seed samples after they passed through the digestive system.

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

“…The plant DNeasy kit from QIAGEN was used to efficiently process intact seeds and dissected embryos to obtain PCR-quality DNA. The use of forensic botanical evidence from crime scenes for DNA typing is still in the developmental stages for difficult samples such as plant matter from stomach contents and excrement [1,2,7]. In our study, we extracted and analyzed tomato seed's DNA from commercial products such as spaghetti sauce, tomato sauce and canned tomato.…”

“…As another example of the usefulness of vegetable or fruit seeds recovered from stomach contents, tomato seeds were ingested, both before cooking and after a variety of cooking treatments and then chemically extracted for DNA. Our previous work has shown that the average yield (from three DNA extractions) from a single tomato seed (one seed per extraction) that was dissected into two parts was 100 ng and 62.5 ng for exterior seed coat and interior embryo, respectively, and the digested seed DNA yield was approximately equivalent to the fresh seed [1]. High-quality DNA (40 ng total) could be extracted from only half a seed embryo; a minimal sample input of approximately 1 000 ng of fresh starting tissue weight [1,2].…”

“…As our previous work has shown that tomato seeds were collected from five morphologically different fresh tomatoes obtained from local grocery stores [1,2]. Figures 1 and 2 illustrate five cultivars of tomato seeds.…”

“…The purpose of this study is to find the relationship between the microscopic exterior comparison and the molecular biological identification method that will be able to quickly screen tomato seed and recover its DNA for forensic application. Our previous study has selected a single fresh or undigested tomato seed to extract DNA and using amplified fragment length polymorphism (AFLP) method to identify for forensic purpose [1].…”