The Plasma Membrane Purinoreceptor P2K1/DORN1 Is Essential in Stomatal Closure Evoked by Extracellular Diadenosine Tetraphosphate (ApA) in .

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