Comparative physiological and transcriptome analyzes reveal the function of exogenous dopamine in improving the...

Dopamine (DA) is a crucial bioactive substance. It primarily functions as a neurotransmitter in animal nervous systems, where it regulates emotion and motor control. However, its physiological roles in plants, particularly its regulatory mechanisms in abiotic stress responses remain unclear. This study systematically reveals, for the first time, the regulatory effects of exogenous dopamine on salt stress tolerance in grapevines.

Vitis vinifera 'Summer Black' was selected as the experimental material, and six treatments were established, including one salt concentration (200 mmol L^-1 (mM) NaCl) and five dopamine concentrations (0.2, 0.4, 0.6, 0.8, 1.0 mM) under salt stress. Measurements of physiological indicators-such as plant phenotype, pigment content, photosynthetic performance, reactive oxygen species, and antioxidant enzyme activity-were conducted alongside transcriptome analysis.

Growth analyses showed that 0.4 mM DA treatment significantly alleviated growth inhibition induced by salinity (200 mM NaCl), as evidenced by plant height, root fresh weight and root dry weight being maintained at 94.99%, 88.07% and 87.37% of the control group (CK) levels, respectively. Physiological analyses demonstrated that, compared with salt treatment alone, DA treatment reduced relative electrical conductivity by 37.43%, decreased reactive oxygen species (H₂O₂ and O₂ ^-) levels by 23.6%, lowered malondialdehyde (MDA) content by 53.4%, and effectively regulated ion homeostasis, reducing leaf Na⁺ content by 48.2% and Na⁺/K⁺ ratio by 56.0%. Furthermore, DA treatment substantially enhanced photosynthetic efficiency (38.2% increase in Pn) and antioxidant enzyme activities (42.9 - 187.3% increases in SOD, POD, CAT, GPX and GR). Transcriptome analysis revealed that DA-regulated differentially expressed genes (DEGs) were predominantly enriched in glutathione metabolism and plant hormone signal transduction pathways, with particularly notable expression changes in glutathione-S-transferases (GSTs) and auxin signaling-related genes.

Dopamine alleviates salt stress in grape by improving photosynthetic efficiency, antioxidant enzyme activities and maintaining ion balance, meanwhile glutathione metabolism and hormone signaling may be involved in dopamine-mediate salt tolerance, providing insights for its practical use in viticulture.