Poster: Education

Abs # 36: Systemic response to leaf damage: a student laboratory exercise

Presenter:	Scott, Jonathan , scottjj@muc.edu
Authors	Scott, Jonathan  (A)
Affiliations:	(A): Mount Union College

Laboratory exercises which introduce students to plant biology should be interesting, require a quantitative approach, and employ modern methodologies when possible. Unfortunately, inconsistent success of such experiments can lead to student frustration and poor initial experiences in plant science. I have employed native PAGE with peroxidase isozyme activity staining, and spectrophotometric analysis of phenylalanine ammonia lyase (PAL) activity of extracts from wounded pinto beans (Phaseolus vulgaris L. cv. "Pinto") in my organismic biology laboratory course. Ample sample volumes can be prepared rapidly by centrifugation of tissue homogenates in 1.5-ml microfuge tubes. Students investigate the systemic induction of peroxidase and PAL activity in response to leaf wounding. Multiple isozymes of peroxidase appeared in unwounded tissues shortly after primary leaves were wounded by crushing with a glass stirring rod. PAL, which catalyzes the first reaction in the pathway for the biosynthesis of polyphenolic compounds, increased in response to wounding. The results naturally lead students to ask questions about plant defense responses, and the control of gene expression.