Salt stress is one of the main abiotic stress factors affecting plant growth and development. Acetylcholine (ACh) is a potential signaling molecule involved in plant stress resistance and growth, but its role in grapevine stress tolerance remains poorly understood, largely because its exogenous application has not been investigated in grapevines. In this study, we found that 40 μmol/L ACh significantly alleviated salt stress induced by 200 mM NaCl in the Vitis hybrid ‘Summer Black’ (V. vinifera × V. labrusca). Exogenous application of ACh significantly improved plant growth under salt stress, including plant height, stem diameter, root fresh weight, and dry weight, while also increasing chlorophyll content and enhancing photosynthetic efficiency. Additionally, exogenous ACh substantially increased antioxidant enzyme activity and considerably reduced the accumulation of reactive oxygen species and malondialdehyde. Moreover, exogenous application of ACh decreased Na+ uptake and dramatically lowered relative electrical conductivity. Comparative transcriptomic analysis revealed that although salt stress repressed genes involved in photosynthesis and carbon fixation, ACh application effectively reversed this suppression by up-regulating transcriptional programs associated with photosystem, carbon metabolism, peroxisome and hormone signal transduction. Collectively, exogenous ACh enhances salt tolerance in grapevines, providing preliminary insights into ACh-mediated stress tolerance signaling in woody plants.
Zhu et al. (Sat,) studied this question.