Investigating Mechanisms of Potassium Solubilization in Diverse Bacteria from Arabidopsis and Brachypodium Root-Associated Isolates

Abstract

Agricultural systems around the world are using increasingly large amounts of nitrogen, phosphate, and potassium synthetic fertilizers to support modern-day demands. Unfortunately, these fertilizers contribute to greenhouse gas emissions and wash off into natural waterways, posing environmental harm. Climate change further exacerbates the stresses on agricultural systems, leaving them susceptible to crop disease and reduced productivity. A consequence of excessive synthetic fertilizer use and climate change stress is plant nutrient imbalance. Nutrients are essential for a variety of necessary functions; without them, the plant will face stunted growth, low yield production, and other negative side effects. While the Earth’s soil is abundant in nutrients, most of them are bound in soil minerals. Geochemical release processes like mineral weathering are very slow, but minerals can also be processed for plant uptake via microbial mineralization mechanisms. Rhizospheric microbes play a crucial role in making nutrients available for plant uptake. Nitrogen-fixing, phosphate-solubilizing, and potassium-solubilizing bacteria are essential in making these macronutrients bioavailable to support plant growth. This project sought to uncover the potassium-solubilizing bacteria (KSB) within the Arabidopsis and Brachypodium root-microbiome and elucidate the key genes and mechanisms that these KSB employ to make nutrients available for plant uptake. Furthermore, using transposon mutagenesis, this project constructed a mutant library of a select strain, Rhizobacterium sp. PA090, to further investigate the KSB genome. This work will be used to inform further research and guide the development of biofertilizers as a sustainable alternative to the environmentally harmful chemical fertilizers.