Abscisic acid (ABA ) regulates a number of different processes , including ripening and seed dormancy , root growth , leaf senescence , and the phase transition from vegetative to generative growth . ABA is the main hormone stress enabling the plant to adapt to environmental factors such as drought, cold or salinity , which mediates the regulation of stomatal thereby controlling water flow and affecting the expression of genes related to stress . A spectacular achievement in understanding ABA signaling pathways in recent years was to identify three distinct ABA receptors : FCA protein involved in the regulation of flowering , H subunit of Mg- chelatase and GCR2 protein superfamily of receptors conjugated protein G. The first -known nuclear receptor was binding protein FCA RNA interacting proteins and PCFS4 FY operating in the formation of the end 3'RNA . FCA - FY complex - PCFS4 prevents accumulation FLC gene transcript encoding a FLOWERING inhibitory transcription factor . The second intracellular receptor is a subunit of the magnesium chelatase CHLH , the enzyme responsible for the incorporation of Mg 2 + to protoporfirynyIX . ABA binding CHLH regardless of protoporfirynyIX and plays a key role in the so-called . retrogratywnym pathway transmitting information from the chloroplast to the nucleus. CHLH/GUN5 is also plastid ABA receptor functioning as a positive element in the signaling pathway responsible for most of the response to ABA . In contrast to the two intracellular receptors , binding ABA GCR2 protein , membrane-associated , interacts with G proteins heterotrimerycznymi ABA binding dissociation forces GCR2 G ? initiating a signaling cascade dependent classical G protein We do not know whether it is typical GCR2 protein coupled receptor protein- G or only peripherally related to the membrane. Notwithstanding the achievements of meeting ABA receptors , the latest research results show that the ABA signaling network occupy a key place specifically interacting with each other phosphatases and protein kinases . Results of genetic and biochemical studies have confirmed participation SnRK2 type kinases in the regulation and SnRK3 stomatal movement , and in the regulation of transcription and RNA metabolism , and in responses to stress factors.