The present invention relates to methods for increasing the stress tolerance in plants and plant cells whereby neonicotinoid compounds, such as but not limited to imidacloprid, clothianidin, thiamethoxam, dinotefuran, nitenpyram, acetamiprid or thiacloprid, are applied to plants, or cells thereof, which comprise a genome that has been modified to make the plants or their cells more stress tolerant i.e. plants engineered to be stress tolerant. Particularly effective stress tolerance synergists in combination with genetically modified stress tolerant plants or their cells are neonicotinoid compounds which comprise a chloropyridine side chain, like e.g. imidacloprid, thiacloprid, acetamiprid, nitenpyram and 6-chloronicotinic acid (6-CNA).
