DNA Fingerprinting of Trout Lilies: A High School Student Project

Abstract

IN May 1996, six high school students and two instructors participated in a three-week course (six hours per day) on applications of DNA fingerprinting to permit students to experience the entire scientific process directly (from designing and conducting original research to presentation and submission of the findings). The specific project involved using DNA fingerprinting to assess the level of genetic variability in a species of trout lily, Erythronium americanum, and determining how the total diversity was subdivided within and among populations of individuals. Individual leaf samples were collected from plants in five populations and nucleic acids were isolated from each. The Polymerase Chain Reaction (PCR) was used with random primers to amplify genetic loci in RAPD (Random Amplified Polymorphic DNA) analyses (Williams et al. 1990; Demeke & Adams 1994). The banding patterns of the amplified products on agarose gels were analyzed for genetic relationships among individuals and populations. Trout lilies are ephemerals, wildflowers that are found only in early spring. They usually grow in dense populations in temperate zone forests (Hughes 1992). E. americanum has yellow petals and is one of two species of trout lilies found in Indiana (E. albidium has white petals) (Gleason & Cronquist 1991). These species belong to the family Liliaceae, a large group of highly variable herbaceous monocotyledons that have underground bulbs (Walters & Keil 1977). Thus, it is believed that they may reproduce sexually or asexually. Hypothetically, the greater the geographical distance that separates populations of E. americanum, the more genetic variation expected among them. In addition, the total genetic variability within this species might be low, reflecting a high degree of vegetative reproduction. On the other hand, frequent sexual