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Dinucleoside polyphosphates (Np_nNs) are considered novel signalling molecules involved in the induction of plant defence mechanisms. However, Np_nN signal recognition and transduction are still enigmatic. Therefore, the aim of our research was the identification of the Np_nN receptor and signal transduction pathways evoked by these nucleotides. Earlier, we proved that purine and pyrimidine Np_nNs differentially affect the phenylpropanoid pathway in <i>Vitis vinifera</i> suspension-cultured cells. Here, we report, for the first time, that both diadenosine tetraphosphate (Ap₄A) and dicytidine tetraphosphate (Cp₄C)-induced stomatal closure in <i>Arabidopsis thaliana</i>. Moreover, we showed that plasma membrane purinoreceptor P2K1/DORN1 (does not respond to nucleotide 1) is essential for Ap₄A-induced stomata movements but not for Cp₄C. Wild-type Col-0 and the <i>dorn1-3 A. thaliana</i> knockout mutant were used. Examination of the leaf epidermis <i>dorn1-3</i> mutant provided evidence that P2K1/DORN1 is a part of the signal transduction pathway in stomatal closure evoked by extracellular Ap₄A but not by Cp₄C. Reactive oxygen species (ROS) are involved in signal transduction caused by Ap₄A and Cp₄C, leading to stomatal closure. Ap₄A induced and Cp₄C suppressed the transcriptional response in wild-type plants. Moreover, in <i>dorn1-3</i> leaves, the effect of Ap₄A on gene expression was impaired. The interaction between P2K1/DORN1 and Ap₄A leads to changes in the transcription of signalling hubs in signal transduction pathways.