Temperature governs fitness effects of transgenes on plants non-monotonically: a global meta-analysis

The global expansion of genetically modified plants supports modern food and ecological security1, yet whether the fitness cost--widely assumed to limit their spread after escape--actually operates in the wild has remained unclear, with empirical evidence remaining mixed2-4. Here, a global meta-analysis of 518 experiments across 48 species reveals that this safety brake is real in the laboratory (fitness cost: [~]13%) but is largely attenuated in the worlds most intensively cultivated croplands. A phylogenetically robust, hump-shaped relationship between mean annual temperature and fitness effect is defined, with fitness benefits emerging specifically within 9.9-22.8{degrees}C. This buffer window overlaps the productive croplands5, where the high-risk proportion (HRP; the area-weighted posterior probability of non-negative fitness effect) consistently exceeds that in natural vegetation and expands with global warming (cropland: +18.4% versus natural vegetation: +8.3% under SSP5-8.5). Notably, constitutive expression or dual-resistance (resist to both abiotic and biotic stressors) transgene can effectively compress the HRP below 30%, providing a quantitative baseline for management. These findings establish a framework for climate-smart deployment that balances agricultural productivity with ecological safety.