Ethylene Cross-Kingdom Signaling In Beneficial Plant-Microbe Associations

随着人口的增加，未来的粮食安全在很大程度上取决于可持续的农业做法，以确保在对环境影响最小的情况下提高作物生产力。优化与植物相关的微生物群落是一种可能的策略。乙烯气体是由植物产生的，它是一种植物激素，已知它影响许多过程。初步发现表明，乙烯受体不仅存在于植物中，也存在于细菌中。这些细菌中有许多与植物有关，但没有一种是致病的，因此植物产生的乙烯可能具有调节有益植物与微生物相互作用的功能。乙烯在植物与微生物相互作用中的作用的研究结果将为改善植物与有益微生物之间的关系以提高粮食生产和安全提供所需的信息。这项研究还将通过扩大UT-Knoxville大学本科生和研究生从事现代生物学研究的机会来增加教育基础设施。该项目将测试植物产生的乙烯通过调节生物膜的形成和细菌对植物的附着来介导一些有益细菌在根际的建立的假设。初步数据表明，几种非致病性和非共生但可能有益的变形菌的基因组编码植物乙烯受体的同源物，其中巴西氮螺旋菌的同源物在体外结合乙烯。进一步的证据表明，细菌的乙烯感应调节了生物膜的形成。乙烯信号的分子机制和细菌的相关反应将在遗传可适应的细菌模型中使用遗传和生化方法的结合来表征。乙烯信号在调节有益菌根表面定植中的作用将在模型植物和作物植物中使用植物定植试验结合乙烯信号的遗传或化学操作来研究。植物和有益菌之间的乙烯信号传导调节植物免疫反应的可能性也将被测试。该研究的结果将产生植物-细菌信号的新模型，从而产生创新的策略来设计根际有益的植物-微生物关联。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With an increasing human population, future food security largely depends on sustainable agricultural practices that ensure elevated crop productivity with minimal environmental impact. Optimizing the microbial community that associates with plants is a possible strategy that is being pursued. Ethylene gas is produced by plants and functions as a plant hormone where it is known to affect many processes. Preliminary findings demonstrate that ethylene receptors are present in bacteria as well as plants. Many of these bacteria associate with plants and with none being pathogenic, it follows that ethylene produced by plants may function to regulate beneficial plant-microbe interactions. Results from this research on the role of ethylene in plant-microbe interactions will provide information needed to improve associations between plants and beneficial microbes to enhance food production and security. The research will also increase educational infrastructure by broadening opportunities for undergraduate and graduate students at the UT-Knoxville to engage in modern biological research. The project will test the hypothesis that ethylene produced by plants mediates the establishment of some beneficial bacteria in the rhizosphere via regulating biofilm formation and attachment of the bacteria to the plants. Preliminary data demonstrate that the genomes of several non-pathogenic and non-symbiotic, but potentially beneficial, proteobacteria encode homologs to plant ethylene receptors, with the Azospirillum brasilense homolog binding ethylene in vitro. Further evidence suggests that ethylene sensing by the bacteria modulates biofilm formation. The molecular mechanism of ethylene signaling and associated responses in bacteria will be characterized using a combination of genetic and biochemical approaches in genetically amenable bacterial models. The role of ethylene signaling in modulating root surface colonization by beneficial bacteria will be studied using plant colonization assays combined with genetic or chemical manipulation of ethylene signaling in model and crop plants. The possibility that ethylene signaling between plant and beneficial bacteria functions to modulate plant immune responses will also be tested. Results from the proposed research will generate novel models for plant-bacteria signaling that could yield innovative strategies to engineer beneficial plant-microbe associations in the rhizosphere.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.