SGER: Diazotrophic Yeast of Poplar Trees

这是一笔用于探索性研究（SGER）的小额赠款，用于验证微生物生理学的重大发现，对生态学、进化生物学和农业具有重要意义。生活在植物体内的微生物被称为内生菌，它们可以通过各种方式显著促进植物生长。虽然内生菌是植物生长的重要因子，但对许多重要作物的内生菌多样性和功能的深入研究尚未开展。杨树是一种快速生长的树木，用于生产纸张和木材。它还可以用于能源的生产，以及污染物的修复。这种经济上重要的物种的内生群落包括各种各样的微生物，其中许多是重氮营养的（固氮）。在对杨树固氮内生菌的研究中，一些初步证据表明，其中一些菌株是酵母。这是一个危险的发现，需要通过严格的实验来验证，因为迄今为止，重氮化只发生在原核微生物（细菌和古细菌）中。因此，本研究旨在明确地测试从杨树中分离的酵母菌是否不含原核污染物，并且实际上是在固定大气中的氮。这些测试将包括生长和生化分析，以及基因克隆、测序和基因表达，这些基因编码参与固氮的酶。如果结果是积极的，这将意味着我们目前对固氮的理解的范式转变，因为它将是固氮真核生物的第一个例子。这项研究可能对农业和环境科学产生重大影响。将豆科植物/根瘤菌共生的固氮能力扩展到非豆科作物，以减少我们对化肥的依赖，一直是人们追求的目标。对酵母菌株的研究可以明显地将大气中的氮转化为非豆科作物的可用形式，这不仅可以将其应用于其他非豆科作物，而且还可以将这种能力转移到作物本身。它还将对理解地球上生命的进化产生深远的影响，并迫使人们重新考虑生态系统中氮循环的模型。其他更广泛的影响将包括培养本科生和研究生的机会，以及对女性从事科学的支持。与高中生和美国杨树种植者的接触也将纳入该项目。

This is a Small Grant for Exploratory Research (SGER) to validate what could be a dramatic discovery in microbial physiology with important implications for ecology, evolutionary biology and agriculture. Microorganisms that live within plants are called endophytes, and they can dramatically enhance plant growth in various ways. Although endophytes provide essential factors for plant growth, in-depth studies into the diversity and function of endophytes of many important crop plants have yet to be performed. Poplar is a fast-growing tree that is used for the production of paper and lumber. It can also be used in the production of energy, and in the remediation of pollutants. The endophytic community of this economically-important species includes a diverse range of microorganisms, many of which are diazotrophic (nitrogen-fixing). While studying the nitrogen-fixing endophytes within poplar trees, several lines of preliminary evidence have indicated that some of the isolates were yeasts. This is a risky finding that needs to be validated with rigorous experiments because to date, diazotrophy is only known to occur in prokaryotic microogranisms (bacteria and archaea). Accordingly, this proposal aims to test unequivocally, whether the yeast isolates from poplar are free of prokaryotic contaminants and are, in fact, fixing atmospheric nitrogen. These tests will involve growth and biochemical assays, as well as gene cloning, sequencing and expression of genes that code for enzymes involved in nitrogen fixation. If the results are positive, it will mean a paradigm shift in our current understanding of nitrogen fixation since it would be the first example of a nitrogen-fixing eukaryote.This research could have a major impact on agricultural and environmental science. It has long been a goal to extend the nitrogen-fixing ability of the legume/Rhizobium symbiosis to non-legume crops in order to reduce our dependence on chemical fertilizers. The study of yeast strains that can apparently transform atmospheric nitrogen into usable forms for a non-legume crop could lead not only to its application on other non-legumes but also to methods of transferring this ability to crop plants themselves. It will also have profound implications in understanding the evolution of life on earth, as well as forcing a reconsideration of models of nitrogen cycling in ecosystems. Other broader impacts will include opportunities for training undergraduate and graduate students, as well as support for women in science. Outreach to high school students and U.S. poplar growers will also be integrated in to the project.