Novel Insights in Ethylene-related Metabolism and its Role in Plant Stress

Ethylene is a small but mighty molecule in the plant world. It ‘shapes’ plant life by regulating growth and development, plant-ecosystem interactions through bi-directional communication with neighboring plants, as well as with microbes in rhizo- and phyllosphere. Its precursor ACC can, besides being converted to the hormone, also be conjugated. Our knowledge on the role of those conjugates is limited. One of the essentials in the toolkit to advance that knowledge is the ability to quantitatively measure these molecules; therefore, we recently established a robust LC-MS/MS approach to quantify ACC and its 3 known conjugates. This allows us to explore their accumulation in response to different stresses and better understand regulatory aspects of ACC and ethylene metabolism, which is particularly important given that ACC plays a signaling role on its own. Understanding how plants adapt their physiology to overcome severe stress conditions is also vital in light of the current climate crisis. This remains a challenge given the complex nature of the underlying molecular mechanisms. To provide a full picture of stress mitigation mechanisms, an exhaustive analysis of publicly available stress-related transcriptomic data was conducted. We combined a meta-analysis with an unsupervised machine learning algorithm to identify a core of stressrelated genes. To ensure robustness and biological significance of the output, often lacking in meta-analyses, a three-layered bio-validation was incorporated. The results present a ‘stress gene core’, a set of key genes involved in plant tolerance to a multitude of adverse environmental conditions rather than specific ones. A majority of these genes are linked to the plant hormone ethylene. In addition, we provide a biologically validated database to assist in design of multi-stress resilience. Taken together, our results pave the way towards a more profound understanding of ethylene biology, and a future-proof sustainable agriculture.