Heat stress reduces soybean yield and can affect market-critical traits like protein and oil concentration. Developing new, heat tolerant soybean varieties through conventional breeding strategies is extremely difficult, because of the logistical constraints inherent in conducting heat stress experiments. In a prior project supported in part by NCSPA, we used a strategy to identify protein markers, hereafter referred as phosphomarkers, that can be used for breeding heat-tolerant soybeans. We conducted growth chamber experiments and field experiments that measured agronomically relevant traits, including yield, protein concentration, and oil concentration, upon heat stress. In addition to the identified phosphomarkers, we now aim to complement this research to identify genetic markers, giving us a holistic view of heat stress responses in soybean. To this end, we will leverage the available leaf samples and perform transcriptomics to identify genes that regulate heat stress responses in heat-tolerant and heat-sensitive soybean genotypes. Using the tissue stored from experiments conducted in 2020 and 2021, we will measure gene expression, identify genes that are central to regulating heat stress tolerance, and link those genes with agronomic outcomes using machine learning-based analytical pipelines aimed at predicting causal-effect relationships.

1. Identify genes that are expressed differently in heat tolerant and heat sensitive soybean varieties.
2. Identify genes that predict better yield and seed composition after heat stress.

Expected End Products: Gene(s) that can be used to screen soybean varieties for heat stress in soybean breeding or that can be targeted for soybean improvement using biotechnology.

Soybean yield and seed quality, particular seed oil concentration, can be reduced by short-term heat waves as well as longer-term, warmer temperatures. This threatens growers’ bottom line and soybean’s competitiveness in the oilseed market. Hot weather is becoming more common, average growing season temperatures are getting warmer, and extreme temperatures occur more frequently. Breeding heat-tolerant varieties using conventional breeding strategies is difficult, because it is not possible to experimentally raise the air temperature over hundreds of soybean lines to select lines with the best heat response. Instead, a strategy that incorporates more in-depth data from fewer varieties is needed to identify genes that can help improve soybean heat tolerance.