Investigating the role of AtVAMP714 in Arabidopsis root development

Abstract

This thesis examines the potential of a role for AtVAMP714 (Vesicle Associated Membrane Protein 714) root development of Arabidopsis thaliana.
The VAMP714 gene was identified as having a possible role in plant development by activation tagging. In this thesis is described a bioinformatics study on the gene and predicted protein, describing its expression and predicted protein localisation and structure. Evidence is presented that the VAMP714 gene is transcriptionally expressed in the root of Arabidopsis and up-regulated by auxin. The protein, a predicted vesicle-associated R-SNARE (Soluble NSF Attachment Protein Receptor), is likely to be localised to the plasma-membrane, Golgi apparatus and vesicles. Loss-of-function tDNA insertion and dominant negative mutants were analysed for phenotypic effects, and the results presented show that VAMP714 function is required for correct root gravitropism and architecture in Arabidopsis, in particular for primary root growth and total lateral root number but not lateral root density or elongation. A novel cell staining technique was developed to improve observation of starch accumulation in cells of the root stem cell niche, and it was found that VAMP714 is required for correct maintenance of stem cell identity in the columella initials.
In light of other experimental data generated in this laboratory, these results support a model for the involvement of VAMP714 in root development through mediating PIN localisation and auxin transport in the root tip.