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

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。旱地土壤是复杂微生物群落的家园，这些微生物群落调节着对人类和地球健康至关重要的过程，包括水的可持续性、土壤肥力、粮食安全、生物多样性和大气二氧化碳浓度的变异性。旱地对干旱的影响特别敏感；全球约20%的旱地被归类为“退化”或“边缘”，每年造成约3000亿美元的损失。土壤微生物通过进入干燥诱导的微生物休眠而持续存在于干燥土壤中。旱地微生物进入和退出干燥引起的休眠的机制还知之甚少。这项研究项目调查了不同的细菌群体如何解决干燥生存的问题。将要研究的土壤细菌是旱地土壤碳循环和农业健康的丰富介体。因此，研究土壤细菌的脱水耐受性机制可以影响如何预防或恢复退化的旱地生态系统的决策。这一结果还可以带来新的方法来衡量专注于减少灌溉的农业实践将如何影响调节土壤肥力的微生物。该项目旨在吸引、培训和留住在STEM领域历来被排除在外的本科生，作为建立多元化的美国STEM劳动力的更大愿景的一部分。这项研究的目标将由学生进行基于课程的真实干旱研究--这是一个具有全球和地方重要性的话题。指导培训计划将教育研究生进行有效的指导，并为他们提供真实的指导经验。干燥土壤中的微生物面临着由于温度和干旱的增加而导致严重土壤干燥的极端压力。尽管旱地中的非芽胞形成土壤细菌在干燥诱导的休眠过程中可以在没有水的情况下一次存活数月，但控制其对长期干燥的耐受性和弹性的分子系统在很大程度上是未知的。具体地说，干燥对RNA的影响--遗传信息和功能蛋白质之间不稳定的分子桥梁--实际上是未知的。水可获得性调节RNA稳定性，进而控制脱水耐受性的假设将得到检验。为了验证这一假设，首席研究员和一组研究学生将通过以下方法量化不同土壤细菌培养物中脱水耐受性和RNA稳定性的关系：1)测量非芽胞形成土壤细菌的脱水耐受性；2)将干燥耐受性与干燥后的mRNA活性联系起来；以及3)计算干燥和复水土壤细菌中基因解析的RNA半衰期。确定细菌脱水耐受性的分子控制对于在可见的地上变化之前了解旱地的脆弱性至关重要，并将为更适合受干旱影响的农业系统的土壤接种剂的开发提供信息。主要研究人员和学生研究团队将通过基于课程的研究活动来解释不同RNA的稳定性如何影响不同土壤细菌的脱水耐受性。首席研究员将应用创新的研究生导师培训计划，将历史上被排除在外的研究生和本科生联系起来。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.