Transcriptional Insights into Soybean Genotypes Under Prolonged Heat Stress: Identification of Key Genes and Soil Influences for Enhanced Tolerance

• Soybean transcriptome reacts differently to prolonged heat stress across different cultivars. • Soil conditions including microbiome and nutrient availability affects how soybean responds to heat stress. • An HsfA2 gene was found in a conserved response to heat stress. Heat stress is increasingly a problem in global agriculture production, both in occurrences and durations. Understanding the molecular mechanisms of soybean heat stress response is essential for breeding heat tolerant soybeans. Soybean heat stress studies have primarily focused on response to short periods of stress, however soybean growing regions are consistently exposed to longer and more frequent heat stress events. Additionally, the role of soil-based microbial communities on heat stress tolerance is poorly understood. We used RNA-seq to measure the transcriptional responses in four soybean genotypes exposed to two temperature regimes (control and high heat) and grown in two soil conditions (native soils and autoclaved soils). We hypothesize that the different genotypes will have different heat stress responses and that altered microbial composition or nutrient availability from autoclaved soils impacts soybean response to long-term heat stress exposure. Improving abiotic stress tolerance has been identified as a major topic of importance by the soybean research community as it is paramount for growers to ensure they have successful seasons. This study has identified multiple genes of interest that could be important in developing improving soybean heat stress tolerant varieties. Potential markers were also identified for use in selection of heat tolerant soybeans in breeding programs