Genetic engineering of glycinebetaine synthesis enhances cadmium tolerance in BADH-transgenic tobacco plants via reducing cadmium uptake and alleviating cadmium stress damage

Abstract Cadmium (Cd) is a toxic non-essential elements to plants, and its accumulation in plants can affect human health through the food chain. Glycinebetaine (GB) is an effective osmotic adjustment substance for plants to resist abiotic stress, and it plays important roles in various stresses. To investigate whether endogenous GB accumulation in vivo can enhance Cd tolerance, we used betaine aldehyde dehydrogenase (BADH) transgenic tobacco plants to explore the important role of GB under Cd stress conditions. The results showed that the tobacco exposed to cadmium stress, lead to growth inhibition and biomass reduction, decreased photosynthesis, decreased the absorption of essential minerals and increased oxidative stress. However, GB accumulation in transgenic tobacco plants significantly increased Cd tolerance, as evidenced by the decreased growth inhibition, enhanced photosynthetic rate and reduced reactive oxygen species accumulation. GB can regulate Cd uptake and transport, which results in reduced Cd accumulation. Moreover, GB also reduced K+ efflux under Cd stress and regulated ion transporter genes to maintain element balance. Our findings provide a novel role of GB in enhancing Cd stress tolerance in transgenic plants and thus propose GB as a potential candidate for relieving Cd toxicity in other crops.