Although plants are photoautotrophic organisms, they are composed of many heterotrophic tissue systems, such as roots, flowers, seeds, and developing leaves, that depend on carbon and nitrogen import for growth and development. In general, sucrose and amino acids are transported to the heterotrophic cells from mature leaves. This process is known as assimilate partitioning and it is a fundamental activity that allows plants to function as multicellular organisms.
My laboratory provided the first biochemical and molecular descriptions of several plant sugar and amino acid transport systems that are key contributors to resource allocation within cells and between organs. We initially described these transporters using an in vitro biochemical assay that allowed us to define the transport properties and bioenergetics of these important carriers. To identify the genes encoding the plant's sugar and amino transporters, we used functional complementation of yeast transport mutants with plant cDNA expression libraries (PNAS 90:7441-7445). The yeast system is very useful because it allows us measure key transport properties and protein structure/function relationships when plant transport proteins expressed in yeast cells (PNAS 95:9025-9030).
The unifying theme of our research today is understanding how plants regulate resource allocation between "source and sink" tissues. To tackle this complex question, we are using genetic and biochemical strategies to identify the signal transduction pathways that regulate assimilate partitioning. We discovered a unique sucrose-mediated signal transduction pathway that regulates the expression and protein abundance of the sucrose transporter that is responsible for phloem loading (PNAS 95:4784-4788; PNAS 99:10876-10880). In a complementary biofuels research project, we are using genetic and genomic tools in rice as a model plant to identify genes that control primary productivity (biomass per m2). In addition to advancing the understanding of fundamental processes in plant growth and development, our research will allow us to develop rational strategies to improve crop productivity for both food and fuel.
Bush DR 2009. Overlook agricultural research at our peril. Proc. Natl. Acad. Sci. USA 106: E108
Weyer KM, Bush DR, Darzins AL, and Willson BD 2009. Theoretical maximum algal oil production. BioEnergy Research (DOI 10.1007/s12155-009-9046-x)
Bush DR and Leach J 2007. Translational Genomics for Bioenergy Production: There’s room for more than one model. Plant Cell 19: 2971-2973
Liu X and Bush DR 2006. Expression and transcriptional regulation of amino acid transporters in plants. Amino Acids 30:113-120
