Audrey Ragsac
Audrey Ragsac
Faculty Advisor: Klaas Van Wijk
Year: 2011

Investigating the Function of β-Amylase5 in Maize Leaf Development and Differentiation

When photosynthesis ceases during the night, sugars become available to plant systems by the breakdown of starch stored in chloroplasts. In vitro, β-amylases (BAMs) degrade starch by hydrolyzing an α-1,4-glycosidic linkage from the reducing ends of polysaccharide chains to form maltose. However, despite this characterization in vitro, their function in vivo remains unclear. In maize (Zea mays), BAM5 accumulates at high levels in the non-photosynthetic base of leaves, showing a different expression pattern than other amylases. Restricted to mesophyll cells that contain little to no starch, BAM5 expression levels peaked at 3-4-cm from the leaf base. Along the C4 leaf development gradient this particular area is a sink-source transition zone in which plastids are heavily investing in the protein synthesis capacity. Functional analysis of BAM5 in maize may reveal unknown features of the sink-source transition process, helping us to better understand the inner-workings of C4 plant development and metabolism. The goal of my project was to purify BAM5 antigen from maize for antibody production. These antibodies will be used in future immunohistochemical studies of the protein.

My Experience

Working in a proteomics lab, I used techniques such a genotyping, RT-PCR, gene cloning, SDS-PAGE, western blot, and protein purification. While greatly enhancing my scientific abilities, this internship afforded me a preview of life as a graduate student in the sciences. Over the course of the summer, I have worked with great mentors and made amazing friends. I am extremely thankful to both the van Wijk Lab and the PGRP program for giving me this incredible experience.