BioPoplar: A Tunable Chassis for Diversified Bioproduct Production
Authors:
C. Robin Buell1*, Christopher Dardick2, Wayne Parrott1, Bob Schmitz1, Patrick Shih3, C. J. Tsai1, and Breeanna Urbanowicz1
Institutions:
1University of Georgia; 2Agricultural Research Service, U.S. Department of Agriculture; and 3University of California–Berkeley
Abstract
Domestication and breeding efforts have shown that selection of specific plant architecture traits across a wide array of plant species, both annuals and perennials, results in improved traits for human use, either for food, feed, or fuel. Similarly, selective breeding can yield distinct chemotypes of crops with desired chemical profiles or compositions. Today, precise knowledge of gene regulation and function can be generated through high-resolution omics technologies, and a synthetic biology toolkit can be constructed to engineer plant genomes at the DNA sequence, chromatin accessibility, and expression levels. Thus, society has entered an era where it is possible to model, design, and then engineer precise changes in plant genomes that will lead to predictive, modified traits.
In this project, researchers will re-engineer poplar as a multipurpose crop that can be used for bioenergy, biomaterial, and bioproduct production. A cell atlas will be generated that encompasses gene expression, gene regulatory networks, and cis-regulatory elements and is responsible for gene expression at the cell-type level, providing the requisite knowledge base and tools for precision bio-based design and fabrication of multipurpose poplar. The team will couple single-cell datasets with new genome and epigenome editing tools to develop new morphotypes of poplar that have altered tree and leaf architecture. These morphotypes will substantially improve biomass potential via increased stand density and tree integrity, photosynthetic capture, and trichome density, and serve as the foundational chassis. These chassis will have altered ratios of leaves to stems and/or trichome density in which researchers can further engineer cell wall composition and/or novel molecules such as precursors for drop-in fuels, thus making chemotypes of poplar that are ‘customized’ to their biomaterial or bioproduct applications and simultaneously ‘maximized’ in optimal morphotypes. The project will employ an iterative design process in which metabolic pathways are optimized to create unique chemotypes with tailored biomaterial and bioproduct composition.
This project will yield poplar chassis with multipurpose uses including bioenergy, biomaterials, and bioproduct production. The generation of a robust cell-type–specific set of transcription factors and cis-regulatory elements, the ability to modulate gene expression in a high-resolution manner, i.e., that of specific cell types, will enable precision genome engineering of metabolism, a significant advancement in capabilities in modulating plant biochemistry. The change in architecture will be exploited to permit production of bioproducts (drop-in fuel precursors in leaves), biomaterials (modified wood composition) in wood, as well as changes in agronomic production practices such as increased stand density leading to increased yield. Collectively, these engineered chassis and tools provide the platform of a new era for poplar biology, agronomy, and processing.