L.M. Shor, Y-S Guo, J. Furrer, D.J. Gage
University of Connecticut,
Keywords: exopolysaccharides (EPS), micromodel, plant growth promoting rhizobacteria (PGPR), reliable carbon sequestration, rhizosphere, soil
Summary:Plants “lose” up to 50% of the carbon they fix as root exudates that are secreted into the soil. Why would plants pour away such a large fraction of the carbon they fix, rather than using it to build more roots, stems, and leaves? The answer is that root exudates are an essential investment in plant productivity and health. Root exudates recruit and support a diverse microbial community that provides a wide range of essential services to the plant. For example, fungal networks help the plant access phosphorous and redistribute bulk moisture in the soil; soil bacteria fix atmospheric nitrogen, protect the root from pathogens, and produce sticky polymers called exopolysaccharides (EPS) that reconfigures the physical structure of soil and retains moisture at the pore scale; soil protists recycle limiting nutrients and shuttle other elements of the system from place to place. For all these reasons and more, the region of soil supported by exudates, also called the rhizosphere, is one of the most complex, variable, and dynamic systems seen anywhere in science. Therefore, the rhizosphere is also one of the most challenging systems to study. As a result, there are powerful incentives to invest in new experimental techniques that enable predictive understanding of how below-ground processes impact above-ground outcomes. My lab has pioneered, validated, and patented (Shor et al., US # 10101312) emulated soil micromodels (ESMs), a microfluidic technology to emulate real soil rhizospheres. ESMs systematically replicate physical, chemical, and biological features while at the same time enabling direct observation of biological responses down to the micrometer scale and in real time. In this talk I will demonstrate how ESMs enable systematic hypothesis-driven research of rhizosphere processes and make the development of agriculture biotechnology less time-consuming, expensive, and difficult. While touching on emerging directions, I will focus on our published work that has demonstrated that moisture-retaining microbial secretions at least double evaporative resistance and dramatically improve system resiliency, but this functionality is only seen in realistic pore-scale geometries. With the loom of climate change and its increasing demands on our water and food systems, there will be rapidly-increasing demand for more productive and cost-effective sustainable agriculture technology, and increasing demand for food production to serve double-duty as a technology for reliable carbon sequestration. Microfluidics may thus play a central role in efforts to promote a sustainable future.