Physiological mechanisms by which γ-aminobutyric acid regulates the response to cadmium stress in cherry tomato

Cadmium (Cd) is a toxic heavy metal that poses a serious threat to food safety and human health. Cherry tomato is a popular raw-consumed vegetable but easily accumulates Cd. Although Gamma-aminobutyric acid (GABA) is known to alleviate heavy metal stress, its specific mechanisms in cherry tomato remain unclear. Therefore, this study investigated the physiological and transcriptomic mechanisms of exogenous GABA (50 µM) in mitigating Cd toxicity (50 µM) using a high-Cd-accumulating cultivar "Green Emerald". The results showed that GABA application significantly reduced Cd-induced growth inhibition and improved root vigor. GABA decreased Cd accumulation in leaves and roots by 46.89% and 26.06%, respectively, and lowered the translocation coefficient by 28.95%. GABA alleviated oxidative damage by increasing the activities of SOD, CAT, and APX,which decreased the accumulation of H 2 O 2 ,O 2 - and MDA. Subcellular analysis showed that GABA kept Cd poultry within the cell wall(Fcw), reducing its levels in soluble fractions (Fs) and organelles (Fo). This was associated with higher contents of cell wall polysaccharides, which enhanced the cell wall's Cd-binding capacity. Transcriptomic analysis showed that glutathione metabolism and phenylpropanoid biosynthesis were the main pathways regulated by GABA during Cd detoxification. GABA application up-regulated GST and POD-related genes, which promoted GSH synthesis for ROS scavenging and increased lignin deposition for cell-wall Cd immobilization.This study provides a theoretical basis for safe vegetable production in heavy metal-contaminated soils.