Laura Bartley

Research Interests

Grass Cell Wall Synthesis & Regulation

The leaves and stems of grasses (which include the cereals) are an abundant source of carbon for making fuels, chemicals, and materials as an alternative to fossil carbon-derived products, a process termed “biorefining.”  Most carbon in biomass is in the plant’s cell wall. The Bartley Lab seeks to understand cell wall synthesis and regulation toward optimizing plant biomass structure and composition for use in biorefining.  Due to the abundance of grass biomass, their work focuses mostly on switchgrass and rice, a bioenergy crop and well-studied reference grass and globally important crop, respectively.

One target is the enzymes that modify grass cell walls with phenolic acids called hydroxycinnamates (see Bartley et al 2013 Plant Phys for the start of this work). These acids can alter the biophysical properties and usefulness of grass cell walls. For example, ferulic acid attached to xylan can increase cell wall covalent cross-linking and make grass biomass less useful for biofuel production. On the other hand, hydroxycinnamates themselves are useful precursors for synthesis of bio-chemicals and -polymers. Hence, with the applied goal of controlling hydroxcinnamate amounts in cell walls, the Bartley lab is working to identify hydroxycinnamate-incorporating enzymes, their transcriptional, posttranslational, and metabolic control points, as well as hydroxycinnamate physiological functions.

More generally, to support growth of biorefining crops in diverse conditions and marginal lands, the Bartley lab seeks to understand how the genes that control composition and other variables such as cell wall thickness are influenced by the environment. Factors of interest include both biotic (e.g., pathogens) and abiotic factors (e.g., low temperature and water availability). This will allow development of genotypes that have improved composition and cell wall properties in diverse environments and permit tailoring of genotypes for particular environments/regions. A related goal is to understand how cell wall traits influence other agronomic and physiological phenotypes (e.g., photosynthesis, abiotic and biotic stress) and potentially the selective basis for cell wall characteristics.

Root Composition and Development

While above-ground biomass can be harvested for biorefining, root biomass and metabolism can contribute to improving sustainability of plant production. Root architecture (length and branching patterns) allow a plant to acquire nutrients and water. Dense roots can reduce erosion and improve soil nutrient and water retention. Root exudates and polyphenolics (tannins) influence microbial activity and soil aggregation. Root cell wall components, like lignin and the aliphatic phenolic suberin, represent a source of carbon in the soil and might lead to accumulation of soil organic matter that can be stable if untilled or below the depth of tilling (Figure). Thus, root traits hold promise for a short-to-medium approach for carbon storage. Indeed, some studies have found that soil carbon accumulation under switchgrass makes bioenergy production carbon negative. With these ideas in mind, the Bartley lab, along with collaborators at the Center for Bioenergy Innovation, is pursuing understanding of and seeking to engineer root architecture and composition as a potential natural climate solution.

Figure. Roots from a 2-month-old lowland switchgrass plant.

Plant Receptor Like Kinases

On a more fundamental level, expanding knowledge of the signaling pathways that control plant growth, development, and interactions with the environment is essential for improving plant traits for food, feed, and fuel. Plant genomes possess hundreds of receptor-like protein kinases though few of them have identified functions. Those that have been studied function in coordinating multicellular development and in perceiving and responding to environmental stimuli, such as pathogen and damage associated molecular signals. Thus, understanding plant kinase function and up- and down-stream signaling events is another important project in the Bartley Lab.

Reference: Schmer, M. R., Liebig, M. A., Vogel, K. P., & Mitchell, R. B. (2011). Field-scale soil property changes under switchgrass managed for bioenergy [https://doi.org/10.1111/j.1757-1707.2011.01099.x]. GCB Bioenergy, 3(6), 439-448. https://doi.org/https://doi.org/10.1111/j.1757-1707.2011.01099.x

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