Friday, March 6, 2009

Rebecca Smith


(Former Lab Member)

I graduated with my B.Sc. (Honours) from the University of Manitoba in 2008.Through my undergraduate studies, I became interested in plant biochemistry, specifically plant secondary metabolism. I did my honours project under the supervision of Dr. David Bird and I examined the ultrastructure of the glandular secretory trichomes of Artemisia annua. Artemisia annua is an important medicinal plant because it produces and sequesters the antimalarial secondary metabolite artemisinin within its glandular secretory trichomes. This research initiated my interest in microscopy, cell biology and the connections between plant cell biology and biochemistry.

I transferred to the PhD program after completing my first year of graduate studies as a Masters student. I was involved in the “Working on Walls” network funded by NSERC and I was co-supervised by Dr. Lacey Samuels and Dr. Brian Ellis. I continued to study plant secondary metabolism for my PhD project as I studied the lignification of plant secondary cell walls.

Lignification of plant cell walls is essential for the maintenance of cell structure and function, especially if the lignified cell undergoes programmed cell death during development, as is the case for water conducting tracheary elements. Lignin plays an important role in plants, but causes problems in industry because it is very difficult, and costly, to degrade or extract from cell walls. The degradation or extraction of lignin from cell walls is integral to the pulp and paper industry, to the development of forage crops, and to the development of ethanolic biofuels. In order to successfully decrease or alter cell wall lignin content to ease lignin degradation without affecting plant survival, all stages of lignification must be studied. I investigated a putative stage of lignification called the “good neighbour”, or co-operative, model. Studies in the Zinnia cell culture system have indicated that the lignification of tracheary elements continues even after programmed cell death, prompting speculation that parenchyma cells surrounding the tracheary elements may be contributing to the lignification of the tracheary elements in a co-operative manner. I used a technique called autoradiography to examine the distribution of radiolabeled lignin precursors within Arabidopsis thaliana roots and stems to determine if the parenchyma cells surrounding tracheary elements are contributing to lignification.