Understanding the ability of hybrids of genetically modified (GM) soybean and wild soybean to survive and reproduce under unfavorable conditions is critical for answering questions regarding risk assessment and the existence of transgenes in the environment. To investigate the effects of high-temperature stress on soybean growth and competitive ability, the GM soybean DBN8002, which expresses the VIP3Aa and PAT proteins, and F₂ generations derived from a cross between GM soybean and NJW (wild soybean) were placed in a greenhouse with an elevated temperature (38/32 °C) for 14 days, and the plant agronomic performance and foreign protein levels of hybrid soybean were evaluated to observe their responses to high temperature. The results revealed that the VIP3Aa and PAT protein levels in F₂ and GM were not influenced by high-temperature stress. In contrast, the pollen germination, pod number, hundred-seed weight, and seed vigor of the F₂ hybrid and parent soybean plants decreased after high-temperature stress. However, except for the number of fully filled seeds per plant, the above parameters of the F₂ hybrid were similar to or slightly lower than those of wild soybean, and no significant difference in fitness was observed between the F₂ hybrid and wild soybean, indicating that the growth and competitive ability of the hybrid were similar to those of its female parent under heat stress conditions, resulting in the transgenes persisting and spreading within agricultural ecosystems. Our results enhance the understanding of the GM soybean plant’s response to heat stress, lay the foundation for breeding heat-resistant soybean varieties, and provide new insights and advanced information on the ecological risks arising from the escape of transgenes.

Gene escape from genetically modified (GM) soybean may have ecological and genetic effects on wild populations. To assess the potential risks associated with backcrossing GM soybean with wild soybean, seed dormancy, inheritance of herbicide resistance, and plant growth in F₁, BC₁F₁, and BC₂F₁ lines were comprehensively analyzed. The results showed that, compared with those of wild soybean, the seeds of BC₁F₁ and BC₂F₁ also exhibited dormancy, albeit at significantly lower levels. BC₁F₁ and BC₂F₁ showed reduced biomass (by 6–7%; p > 0.05) and inferior reproductive performance, with the numbers of pods, seeds, and filled seeds per plant decreasing by 27.02–29.57% (p < 0.05). However, glyphosate spraying tests demonstrated that 46.3% of the BC₁F₁ plants and 30.6% of the BC₂F₁ plants were resistant to glyphosate. Moreover, exogenous protein assay results confirmed that the exogenous gene was stably inherited in these plants, which confers a significant growth advantage under selection pressure. These findings provide new scientific evidence for assessing the ecological risks associated with the environmental release of GM soybean.