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.
