Professor Moffatt started working on adenine phosphoribosyltransferase (APT) when she was a postdoctoral fellow and found that loss of the predominant isoform, APT1, made plants male sterile. Recently Professor Moffatt has returned to looking at this enzyme activity because of the identification of fertile APT1-deficient mutant. Analysis of this mutant has led to our current studies of the dual transcripts arising from the APT1 locus. The two APT products reside in different compartments but the functional significance of this targeting is under investigation. Understanding APT1’s role in plant physiology is particularly intriguing because the fertile APT1 mutant line is more stress tolerant than wild-type plants.
Professor Moffatt and her research group have been looking at the roles of adenosine kinase (ADK) in plants for several years. The generation and analysis of lines deficient in ADK activity has revealed that this enzyme plays a critical role in maintaining methylation activities in plants and its expression is regulated in association with cellular methylation requirements. ADK deficiency also impacts cytokinin metabolism. Studies of ADK led us to look at related enzymes associated with methylation, particularly their subcellular localization and protein-protein interactions.
One of her team's recent projects is focused on mutants deficient in methylthioadenosine (MTA) nucleosidase activity. The most deficient mutant is multiple problems including male and female sterility, abnormal vascular development, reduced auxin transport and lower nicotianamine content. Their results indicate that this phenotype is due to MTA feedback inhibition of several key enzyme activities including those that catalyze the synthesis of polyamines and nicotianamine. Interestingly, polyamine supplementation affects the phenotype of these mutants.
To understand the involvement of these enzymes and metabolites in plant development we analyze mutants in the corresponding genes using genetics, metabolite profiling, enzyme assays, morphological analyses, and reporter gene studies. Immunodetection of protein levels and protein-protein interaction assays are also involved.
Professor Moffatt is also collaborating on a transcriptomic and metabolomic analysis of a naturally stress tolerant plant, Eutrema salsuginea, along with Drs. E. Weretilinyk. G. Gray, R. Cameron and B. Golding (McMaster University).
Funding is available to support a motivated graduate student’s participation in this research. Interested students are welcome to contact Dr. Moffatt by email for further information.
Barbara Moffatt is intrigued by how gene expression and enzyme activities are regulated to meet the metabolic needs of plant growth and development. Her research involves genetics, metabolite profiling, enzyme assays, morphological analyses, and reporter gene studies, as well as immunodetection of protein levels and protein-protein interaction assays.