Enhanced Growth and Stress Tolerance in Plants After Treatment With Ethylene

Enhancing crop yields is a major challenge because of an increasing human population, climate change, and reduction in arable land. Methods to increase growth and stress resistance in plants are key to addressing this challenge. However, the success of these approaches is not guaranteed since improvement in growth often leads to a decrease in stress tolerance and vice versa. This trade-off can have profound implications on bioengineering strategies to enhance plant yield. Plants are regulated by a variety of hormones including ethylene, which is a gas known to regulate many aspects of plant growth, development, and stress responses. We recently discovered that transient ethylene treatment early in seedling development leads to long-lasting changes that increase both growth and stress tolerance. This potentially provides a simple technique to improve plant vigor and yield. We propose to use a variety of scientific approaches to determine the mechanisms for this unanticipated result and develop treatment protocols applicable to a variety of plant species. Results from the proposed research will reveal new paradigms for treating plants and will provide targets for genetic modification to increase plant growth and vigor to improve food security. Overall, this research is expected to have significant impact on crop productivity, and enhance scientific and educational infrastructure and opportunities for students mentored including women and minorities. We recently made the surprising observation that ethylene treatment of germinating seeds in darkness, followed by transfer to light and ethylene-free conditions caused plants to grow much larger and display enhanced abiotic stress tolerance. Correlating with these changes, ethylene pre-treatment also led to long-lasting increases in both photosynthesis and the levels of starch, carbohydrates, and various core metabolites. We hypothesize that transient ethylene treatment of seedlings at critical times in their development results in epigenetic changes that cause long-lasting increases in photosynthesis and carbon metabolism leading to increased carbohydrate levels which enhance both growth and stress tolerance. The main goals of this research will be to test this hypothesis, uncover the mechanisms responsible, and establish how wide-spread these effects of ethylene are across plant species. To do this we propose an integrated set of experiments do determine the signaling pathway(s) responsible and determine the changes that occur in photosynthesis and carbohydrate metabolism. These studies involve multiple spatiotemporal scales and combine genetics, molecular biology, biochemistry, and physiology to provide mechanistic details about enhanced plant vigor. These studies will furnish links between subcellular events and whole plant responses. This research is jointly funded by the Physiological Mechanisms and Biomechanics program in the Division of Integrative Organismal Systems and the Cellular Dynamics and Functions cluster in the Division of Molecular and Cellular Biosciences. 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.