Research projects in the Tsai Laboratory investigate the genetic and molecular mechanisms underpinning tree growth, stress responses and lignocellulosic wood properties, using Populus species (poplars, cottonwoods and aspens) as the primary model organisms.
Secondary metabolism in many tree species is dominated by the phenylpropanoid pathway. In Populus species, structural lignin and non-structural condensed tannins and phenolic glycosides can comprise more than 50% of tissue dry mass. These substances have varied and specific roles in the development and environmental fitness of trees. The molecular regulation of phenylpropanoid composition and overall abundance is therefore important for tree growth, fitness and biomass value. Metabolite profiling, whole genome transcriptome analysis and bioinformatics tools are employed in conjunction with transgenic manipulation and whole plant physiology in addressing these issues.
Lignocellulsoic cell walls account for at least two-thirds of harvested biomass in fast-growing, short rotation bioenergy tree taxa. The structural and chemical properties of cell walls vary in ways that affect biomass utilization. Molecular, biochemical, mutagenesis and transgenic approaches are used to explore and experimentally test the controls of wood formation pertinent to phenylpropanoid and lignin biosynthesis, one-carbon metabolism, and cytoskeletal regulation of cellulose microfibrils.
Better understanding of gene networks at the interface of growth, wood formation and stress response is expected to contribute toward sustainable tree productivity, and is also expected to contribute to ecological investigation using genomic approaches.
