Given the threat of precipitation shortages and increasing droughts in many European countries due to global warming, the search for environmentally friendly approaches to increasing drought resistance in plants is becoming highly relevant. One of them is the treatment of plants with bioactive molecules involved in cell protection. Our preliminary results showed that the foliar application of the amino acids proline and γ-aminobutyric acid (GABA) increased plant resistance to water deficit. The aim of this study was to investigate the effect of exogenous amino acids on the chaperone system that protects cellular proteostasis. Arabidopsis thaliana (Col-0) plants at the rosette stage were sprayed with 0.1 mM proline, 0.1 mM GABA, and a mixture of the two, and then subjected to gradual soil drying up to deep wilting, following by rehydration. Changes in the expression of genes encoding heat-shock proteins (HSP) of different families and stress-inducible heat-shock transcription factors (HSF) regulating the development of the reaction, as well as the accumulation of proline in leaves, were assessed. It was determined that exogenous proline and GABA led to an increase in proline content. A real-time RT-PCR analysis revealed that both amino acids also have specific effects on the dynamics and expression levels of HSPs and HSFs. In addition, the combined application of amino acids showed a complex relationship between their metabolism and function. The obtained results demonstrated a significant influence of exogenous proline and GABA on the protein quality-control system under the conditions of water deficiency and characterised the features and interaction of their action. (EMBO SLG Grant 5437-2023)