Metabolism, biochemistry, biotechnology, amino acids, stress, biotic, abiotic, resistance

Research Interests:

My primary research is concerned with developing abiotic and biotic stress resistance in plants using genetic engineering strategies. My principal approach involves GABA (gamma-aminobutyrate), a ubiquitous 4-C, non-protein amino acid of uncertain function in plants. However, it does accumulate in response to a variety of abiotic and biotic stresses, including temperature and oxygen shock, as well as insect damage. We are continuing to identify the proteins involved in GABA metabolism and transport, and their corresponding genes, using state-of-the- art analytical tools and biochemical and molecular techniques. These genes are typically being expressed in recombinant expression systems, with the recombinant proteins being isolated and purified for biochemical and physical characterization. The genes are also being modified and reinserted by Agrobacterium-mediated transformation or particle bombardment. We are using various Arabidopsis mutants (overexpression, knockout, knockdown) to elucidate the physiological function and regulation of GABA metabolism, and the interactions among GABA metabolism, photorespiration, polyamines and the tricarboxylic acid cycle. Also, we are investigating the role of GABA in the onset of physiological disorders in tree fruit stored under controlled atmosphere conditions. In addition to manipulating GABA metabolism, we are collaborating in studies of N use efficiency and carotenoid metabolism.

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Selected Publications:

Trobacher, C.P., S.M. Clark, G.G. Bozzo, R.T. Mullen and B.J. Shelp. (2012). Catabolism of GABA in apple fruit: Subcellular localization and biochemical characterization of two γ-aminobutyrate transaminases. Postharv. Biol. Technol. 75: 106-113.

Shelp, B.J., G.G. Bozzo, C.P. Trobacher, A. Zarei, K.L. Deyman and C.J. Brikis. (2012). Review/hypothesis: Contribution of putrescine to 4-aminobutyrate (GABA) production in response to abiotic stress. Plant Sci. 193-193: 130-135.

Shelp, B.J., G.G. Bozzo, A. Zarei, J.P. Simpson, C.P. Trobacher and A.L. Allan. (2012). Strategies and tools for studying the metabolism and function of γ-aminobutyrate in plants. II. Integrated analysis. Botany 90: 781-793.

Shelp, B.J., R.T. Mullen and J.C. Waller. (2012). Compartmentation of GABA metabolism raises intriguing questions. Trends Plant Sci. 17: 57-59.

Allan, W.L., K.E. Breitkreuz, J.C. Waller, J.P. Simpson, G.J. Hoover, A. Rochon, D.J. Wolyn, D. Rentsch, W.A. Snedden and B.J. Shelp. (2012). Detoxification of succinate semialdehyde in Arabidopsis glyoxylate reductase and NAD kinase mutants subjected to submergence stress. Botany 90: 51-61.

Allan, W.L., S.M. Clark, G.J. Hoover and B.J. Shelp. (2009). Role of glyoxylate reductases during stress: a hypothesis. Biochem. J. 423: 15-22.

Clark, S.M., R. Di Leo, P.K. Dhanoa, O.R. Van Cauwenberghe, R.T. Mullen and B.J. Shelp. (2009). Biochemical characterization, mitochondrial localization, expression, and potential functions for an Arabidopsis γ-aminobutyrate transaminase that utilizes both pyruvate and glyoxylate. J. Exp. Bot. 60: 1743-1757.

Allan, W.L., J.P. Simpson, S.M. Clark and B.J. Shelp. (2008). γ-Hydroxybutyrate accumulation in Arabidopsis and tobacco plants is a general response to abiotic stress: putative regulation by redox balance and glyoxylate reductase isoforms. J. Exp. Bot. 59: 2555-2564.

Hoover, G.J., O.R. Van Cauwenberghe, K.E. Breitkreuz, S.M. Clark, A.R. Merrill and B.J. Shelp. (2007). Characteristics of an Arabidopsis glyoxylate reductase: general biochemical properties and substrate specificity for the recombinant protein, and developmental expression and implications for glyoxylate and succinic semialdehyde metabolism in planta. Can. J. Bot. 85: 883-895.

Shelp, B.J., A.W. Bown and D. Faure. (2006). Extracellular γ-aminobutyrate mediates communication between plants and other organisms. Plant Physiol. 142: 1350-1352.

Bown, A.W., K.B. MacGregor, B.J. Shelp. (2006). Gamma-aminobutyrate: defence against invertebrate pests? Trends Plant Sci. 11: 424-427.

Chevrot, R., R. Rosen, E. Haudecoeur, A. Cirou, B.J. Shelp, E. Ron and D. Faure. (2006). GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens. Proc. Natl. Acad. Sci. 103: 7460-7464.