Jamell Dacon

The growth of the human population and changes in global environmental conditions compromises food security. Thus, improving the ability of agricultural crops to resist environmental stress and withstand a changing environment is an important objective that will help to overcome challenges in food security. When plants experience environmental stressors, they induce tissue degradation/degeneration through the release of stress hormones such as ethylene. However, plant ethylene levels can be decreased by plant growth-promoting bacteria that produce the enzyme 1-aminocyclopropane-1-carboxylatedeaminase (ACC-d). As a result, ACC-d can facilitate plant growth and development despite the stressor. Our objective is to understand the distribution and diversity of ACC-d genes across different habitats and among microbial lineages, which will provide insights into the breadth and specificity of the relationships between microbes that produce ACC-d and plants. In our approach, we mined shotgun metagenomes from a wide variety of habitats, including marine systems, compost, freshwater, soils, and mammal guts. We found that ACC-d is widespread in many environments but that the greatest diversity and abundance was observed in soil environments. This suggests that bacterial populations that have potential interactions with terrestrial plants are enriched for ACC-d. Thus, there is promise in bioprospecting for effective plant growth promoting bacteria among uncultivated lineages of soil bacteria. The results of this work will improve ecological understanding of microbe-plant interactions during stress, and ultimately contribute insights into leveraging microbe-plants relationships to increase crop production.