CAREER: Just add water? Investigating RNA stability in desiccated soil bacteria.

University Of Arizona, Tucson AZ

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Dryland soils are home to complex microbiomes that mediate processes crucial to human and planetary health, including water sustainability, soil fertility, food security, biodiversity, and variability in atmospheric CO2 concentrations. Drylands are particularly sensitive to the effects of drought; about 20% of global drylands are classified as “degraded” or “marginal,” with an annual cost of ~$300 billion. Soil microbes persist in dry soil by entering desiccation-induced microbial dormancy. The mechanisms that allow dryland microbes to enter and exit desiccation-induced dormancy are poorly understood. This research project investigates how different groups of bacteria tackle the problem of surviving desiccation. The soil bacteria that will be investigated are abundant mediators of soil carbon cycling and agricultural health in drylands. Thus, studying the mechanisms of desiccation tolerance in soil bacteria can influence decisions about how to prevent or rehabilitate degraded dryland ecosystems. The results can also lead to new methods to measure how agricultural practices focused on reducing irrigation will affect the microbes that regulate soil fertility. The project aims to attract, train, and retain undergraduates that are historically excluded in STEM fields as part of a larger vision to build a diverse American STEM workforce. The research aims will be conducted by students conducting authentic course-based research on drought—a topic of global and local importance. A mentorship training program will educate graduate students in effective mentorship and provide them with authentic mentorship experience. Microbes in dry soils face extreme stress from increases in temperature and drought that lead to severe soil drying. Although non-spore forming soil bacteria in drylands can persist without water for months at a time through desiccation-induced dormancy, the molecular systems that control the tolerance and resiliency to prolonged desiccation are largely unknown. Specifically, the effects of drying on RNA—the labile molecular bridge between genetic information and functional protein—are virtually unexplored. The hypothesis that water availability regulates RNA stability, which in turn controls desiccation tolerance will be tested. To test this hypothesis, the primary investigator and a team of research students will quantify the relationship between desiccation tolerance and RNA stability in cultures of diverse soil bacteria by 1) measuring the desiccation tolerance of non-spore forming soil bacteria; 2) relating desiccation tolerance to mRNA activity after drying; and 3) calculating the gene-resolved RNA half-lives in desiccated and rehydrated soil bacteria. Determining the molecular controls of bacterial desiccation tolerance is vital to understand dryland vulnerability ahead of visible aboveground changes and will inform development of soil inoculants better suited to drought-impacted agricultural systems. The primary investigator and student research teams will explain how the stability of different RNAs influence desiccation tolerance in diverse soil bacteria with course-based research activities. The primary investigator will apply an innovative graduate student mentorship training program that connects historically excluded graduate and undergraduate students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.