Molecular interactions between rhizobacteria and wheat under water stress

超过30%的地球表面是干旱的，大多数气候变化模型预测未来干旱的持续时间和严重程度会增加，这将对植物生命产生不利影响。植物适应缺水的部分原因是通过培养与根相关的微生物来增强对环境胁迫的抵抗力。水分限制对植物及其相关微生物之间的分子通讯和相互作用的影响仍然知之甚少。本项目将结合分析化学、生物信息学、遗传学和生理学的方法，研究干旱条件下根定殖细菌synxantha假单胞菌和小麦之间的互利相互作用。这项研究将为干旱土壤中的植物如何招募、塑造和操纵相关微生物以减轻干旱压力提供新的见解。该项目将培养从事各方面研究的研究生和博士后学者。细菌代谢途径的分析将由本科生通过个人研究项目完成，并作为微生物遗传学和生态学课程的一部分。项目组将参与大学项目，并协调旨在招募代表性不足的群体进入科学领域并加强从小学到大学的科学教育的推广活动。这项研究对于开发有益微生物群落以提高作物性能和补充植物育种工作至关重要。本应用的首要目标是在分子水平上了解根定殖（根际）细菌如何在干燥土壤中维持生理活性和与其植物宿主的紧密互惠相互作用。植物可以被视为元生物或整体生物，部分依赖于它们的微生物群来实现特定的功能和特性。最近的研究强调了有益的根瘤菌在植物耐受非生物胁迫（包括干旱）的能力中的重要作用。然而，水分限制对根际植物-微生物交流的影响仍未得到充分的研究。该方法的重点是synxantha假单胞菌2-79，这是一种典型的生物防治菌株，自然适应于在太平洋西北部干旱地区种植的小麦。具体目的是描述与水分胁迫有关的小麦根系分泌物的变化，并将这些变化与2-79的生理学联系起来；利用RNA-seq鉴定2-79对水分胁迫条件的转录反应；并确定在水分亏缺条件下，所选途径对2-79在根系上的持续能力的贡献。预期的结果将有助于了解干旱土壤中的根沉积如何调节参与缓解干旱胁迫的细菌途径，并有助于选择特定类型的有益根瘤菌。该项目还将为正在进行的旨在破译土壤湿度对旱地小麦根际微生物组影响的实地研究提供关键的功能基因组学补充。

Over 30% of the earth's surface is arid, and most climate change models predict future increases in drought length and severity that will adversely affect plant life. Plants adapt to water deprivation in part by fostering root-associated microorganisms that enhance resistance to environmental stresses. The impact of water limitation on molecular communication and the interactions between plants and their associated microbes remains poorly understood. This project will utilize a combination of analytical chemistry, bioinformatics, genetic, and physiological approaches to investigate the mutually beneficial interaction between the root-colonizing bacterium, Pseudomonas synxantha, and wheat under arid conditions. The research will yield new insights into how plants in dry soils recruit, shape, and manipulate their associated microbes to mitigate drought stress. This project will train graduate students and a postdoctoral scholar that will be engaged in all aspects of the research. The analysis of bacterial metabolic pathways will be done by undergraduates via individual research projects and as a part of microbial genetics and ecology classes. The project team will participate in university programs and coordinate outreach activities aimed at recruiting underrepresented groups into the sciences and strengthening science education at the elementary through college levels. This research is crucial for exploitation of beneficial microbial communities to improve crop performance and complement plant breeding efforts.An overarching goal of this application is to understand at the molecular level how root-colonizing (rhizosphere) bacteria maintain physiological activity and tight mutualistic interactions with their plant hosts in dry soils. Plants can be viewed as meta-organisms or holobionts that rely in part on their microbiome for specific functions and traits. Recent studies have highlighted the essential role of beneficial rhizobacteria in the ability of plants to tolerate abiotic stresses, including drought. However, the effect of water limitation on the plant-microbe communication in the rhizosphere remains virtually unexplored. The approach focuses on Pseudomonas synxantha 2-79, a model biocontrol strain that is naturally adapted to wheat grown in arid parts of the Pacific Northwest. The specific aims are to characterize the changes in wheat root exudates that are associated with water stress and to relate these changes to the physiology of 2-79; to identify transcriptional responses in 2-79 to water-stressed conditions using RNA-seq; and to define the contribution of selected pathways to the ability of 2-79 to persist on roots under conditions of water deficit. The expected results will help to understand how rhizodeposition in arid soils modulates bacterial pathways involved in the mitigation of drought stress and contributes to the selection of specific types of beneficial rhizobacteria. The project will also provide a crucial functional genomics complement to ongoing field studies aimed at deciphering the effect of soil moisture on the rhizosphere microbiome of dryland wheat.