The Brutnell lab is focused on understanding photosynthetic differentiation and, in particular, identifying the transcriptional networks that drive C4 photosynthetic development. Applications of this research include improving photosynthetic efficiencies in the emerging bioenergy model system, Setaria viridis, as well as improving yield in existing C4 crops such as maize, sorghum and sugarcane. The lab is also working with a large international consortium to engineer C4 traits into C3 grasses.
A major thrust of this research will focus on the use of new model grasses as drivers for lignocellulosic feedstock development and to improve productivity of major cereal crops. This includes developing genetic resources for Setaria viridis and Brachypodium distachyon. Setaria viridis is a small, self-pollinating diploid and is a member of the panicoid clade of grasses that includes maize, sugarcane, sorghum, miscanthus and switchgrass. Brachypodium distachyon is also a small, self-pollinating diploid grass and is a member of the Pooideae clade that includes wheat, barley, rye and several turf grass and forage species. The genomes of both species have recently been sequenced and transformation technologies have been developed for each. Members of the Brutnell lab have contributed to the development of transformation technologies for Setaria viridis and have helped annotate the S. viridis and B. distachyon genomes. They are currently developing genetic resources for both systems that include chemically- and radiation- mutagenized populations. They are also tapping high-throughput sequencing techniques to accelerate reverse and forward genetic screens and to develop a gene atlas for S. viridis using RNAseq technology.
Another important component of their research program is the development of reverse genetics tools for gene discovery in maize. Over the past ten years, members of the Brutnell lab have been mobilizing and mapping the maize transposable elements Ac and Ds insertions throughout the maize genome. They have also been developing genetic and molecular protocols for using Ac and Ds as insertional mutagens. These elements tend to insert at closely linked sites in the genome to create unstable genetic variation. They have shown how these transposons can be used to fine map gene structure and have several targeted mutagenesis programs underway.
Finally, a fundamental biological challenge that the Brutnell lab is trying to address is to understand the mechanisms that drive C4 photosynthetic differentiation. Using the forward and reverse genetics resources they have developed for S. viridis and Z. mays, they are now generating mutants in the genes necessary for the C4 carbon shuttle and using a combination of informatics and molecular approaches to define the regulatory networks driving their expression. These studies are targeted at understanding the function of genes involved in C4 photosynthesis and have applications in breeding/engineering improved photosynthetic traits in C4 grasses and in introducing novel C4 traits into C3 grasses.