Drought is a serious environmental challenge that significantly reduces soybean yields in the United States. Soybeans are particularly vulnerable to drought because it affects their ability to use nitrogen from the air for growth, a process called symbiotic nitrogen fixation. This makes drought's impact on soybeans more severe compared to non-legume crops like corn. Scientists have been working for decades to find genes that help soybeans withstand drought, but progress has been limited because drought tolerance is a complex trait influenced by many genes. Given these challenges, we have been exploring new ways to improve soybean drought tolerance. This three-year project aims to identify and study genes that respond to drought stress and potentially enhance drought tolerance by modifying these genes. In this first year period, we evaluated overall performance of two single-gene mutants and overexpression lines in the Williams 82 background under drought stress and identified two gene-editing lines with enhanced drought tolerance; we developed early-generation overexpression/editing lines for these two genes using two elite soybean cultivars; In addition, we have identified three additional genes responsive to drought stress and are in the process of developing overexpression/editing lines for potential enhancement of drought tolerance of these elite cultivars; Through this project, we continued to optimize the transformation and gene-editing pipelines that works for elite varieties.

We anticipate that this research project will lead to the development of drought-resistant soybean varieties, as pre-breeding lines for further enhancement. Such varieties would greatly benefit U.S. farmers by making their farming systems more sustainable and economically resilient in the face of changing climate conditions.