Extracellular ATP Receptors P2Ks Play a Role in Regulating Local and Systemic ROS Accumulation of Arabidopsis thaliana Seedlings in Response to Local Salt Stress.

In Arabidopsis (Arabidopsis thaliana), the lectin receptor kinases I.9 (P2K1) and I.5 (P2K2) are known as the receptors of extracellular ATP (eATP) and play important roles in the regulation of the responses of plants to environmental stresses. In the presented work, the possible involvement of these receptors of eATP in regulating local and systemic ROS (reactive oxygen species) accumulation to local salt stress was investigated. The roots or a single leaf of the seedlings were subjected to local salt stress, and the leaves that did not directly experience salt stress were regarded as the systemic organs. The results showed that local treatment with salt stress caused a local and systemic increase in eATP levels. Local application of exogenous ATP to the roots or a single leaf can evoke local and systemic ROS accumulation. Interestingly, local salt stress-induced local accumulation of ROS was weakened by P2K mutations, which also attenuated the systemic accumulation of ROS induced by local salt stress. In addition, local and systemic increases in H₂O₂ (hydrogen peroxide) content and CAT (catalase) activity by local NaCl stress were also reduced by the P2K mutations. These results suggest that the eATP receptors play an important role in regulating local and systemic ROS accumulation in response to local salt stress.