This proposal is a continuation of research that focuses on soybean plants with increased root length and branching to boost yield and resiliency of yield in Tennessee. A strong root system is necessary for maximized plant nutrition, defense, and water use. Drought tolerance is impossible, for instance, without a robust root system, which is especially important in soybean during pod fill. Soybean plants with increased root length and branching would significantly improve water/nutrient uptake efficiency and yield potential in diverse environments. Such improvement is the primary goal of our project. Improving roots, improves crop yield.
Our previous work (TSPB 2018 progress report) identified a number of soybean genes potentially associated with root growth/development as well as promoting tolerance to drought and nutrient deficiency. We successfully overexpresses these “root genes” in soybean plants with transgenic roots and are in the process of assessing their impact on plant growth and seed production by evaluating the biomass weight, flowering time, pod setting, and seed count and weight. Here we propose to continue our research by further discovery and in-depth characterization of these identified soybean genes involved in root growth and stress tolerance to challenging environmental conditions. Discovery and in-depth study of these candidate genes would lead to a roadmap in identifying soybean genes for breeding and developing high yielding soybean varieties.
Additionally, we aim to focus on improvement of drought tolerance, which is a major abiotic stress limiting soybean growth and development. To relieve soybean from drought stress, the plant has to undergo several changes in its developmental strategies. One such strategy is an association with beneficial growth promoting microorganisms such as arbuscular mycorrhizal fungi (AMF). AMF symbiosis protects plants from drought stress by playing a key role in the water-transport process. Furthermore, it increases soil moisture retention capacity. AMF also provides its host plant with immobile micronutrients that are essential for growth and production. This supplement of nutrients significantly helps plants to better survive and increase yields in soils with limiting nutrients. AMF can also protect plants from the soil-borne pathogen.
Soybean yield greatly depends on root system architecture and nitrogen fixation. Several plants genes that are responsible for AMF symbiosis have been identified. Some of these genes are also essential for root nodule symbiosis. Root nodule symbiosis accounts for nitrogen fixation that enhances mineral nutrition of the plant. Critical symbiotic genes initiate symbiosis as well as maintain it. One such example is the aquaporin gene family, which plays roles in both AMF symbiosis and drought stress. They function as water-channel proteins stopping the water flow from the plants to soil under water stress conditions.