Complementation of an AtCAM3 knockout line restores wild type root growth and provides localization data through expression of a chimeric GFP:AtCAM3 fusion protein in Arabidopsis thaliana

Regulation of growth and acclimation to biotic or abiotic stressors involves a multitude of signal transduction events in higher eukaryotes, and oscillations in cytosolic Ca2+ are one highly conserved mechanism for transducing these signals. In Arabidopsis thaliana there are four main isoforms of Calmodulin (CaM), one group of proteins that bind Ca2+ ions and interact with a multitude of protein targets to modulate their activity. These four CaM isoforms are encoded in seven different genes. An additional fifty calmodulin-like proteins (CMLs) also are present in the Arabidopsis genome, allowing for rather complex signaling events to be communicated via Ca2+ signals during different developmental periods and in different tissues. Insertional knockout lines for AtCAM3, which produces an identical polypeptide sequence to AtCAM2 and AtCAM5, exhibit increased susceptibility to heat stress as well as reduction in root growth. This root growth phenotype was not impacted by varying osmotic stress of growth media relative to Columbia wild type plants. Transgenic lines created from AtCAM3 knockout plants expressing chimeric GFP:AtCaM3 exhibited restored root growth and provided localization data for AtCaM3 in vivo. AtCaM3 was shown to localize more highly in cytoplasmically dense cells such as meristematic regions of the root tip and sites of lateral root branching, as well as near cell membranes. Localization was also observed in cell nuclei where it could affect gene expression and explain differences in root growth rate and stress tolerance observed in AtCAM3 knockout plants.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Plant Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Quarles, Devin R.

Contributors dc:contributor

• Zielinski, Raymond E.

• calmodulin
• secondary calcium signaling
• root growth
• Green Fluorescent Protein (GFP)

Statement dc:rights

• Copyright 2011 Devin R. Quarles

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/26312

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/26312