The Role Of Extracellular ATP In Wound Response And Its Relationship With Intracellular ATP

Adenosine 5'-triphosphate?ATP?,a high-energy compound,is usually considered to be localized in organelles,such as the mitochondria,and acts as an intracellular energy currency molecule element to support various metabolic activities of cells.And it is also found in the extracellular matrix of animal and plant cells.Extracellular ATP?eATP?,as a messenger molecule,can increase the content of intracellular Calcium ion(Ca²⁺),Nitric Oxide?NO?,Reactive Oxygen Species?ROS?and other intracellular second messenger molecules to regulate the plants growth process and systemic response to environmental stimuli.So we used bean?Phaseolus vulgaris L?leaves and suspension cells of tobacco?Nicotiana tabacum L.cv.Bright Yellow-2?as experiment material,to study the regulation of eATP on the systemic wound response of bean leaves,and the relationship between eATP and intracellular ATP?iATP?.The main conclusions are as follows:?1?Extracellular ATP can affect the systemic response of bean leaves after mechanical wound.Mechanical wound or exogenous ATP treatment increased the level of extracellular ATP in plant treated leaves?CL?,but there was no significant change in adjacent healthy leaves?SL?.However,wound or exogenous ATP treatment can induce the Hydrogen Peroxide?H₂O₂?,Malondialdehyde?MDA?,Catalase?CAT?,Polyphenol Oxidase?PPO?of CL and SL increased in different levels.Then we used AMP-PCP to further explore the effects of eATP on systemic wound response.Compared with the wounded leaves,the levels of physiological indexes in wounded CL and SL with the AMP-PCP pretreated were significantly reduced.The results showed that the change of eATP had a certain effect on the systemic wound response.?2?H₂O₂ transfer played a role in the regulation of eATP on systemic wound response.Exogenous H₂O₂ can induce the increase of H₂O₂,MDA,CAT and PPO levels in CL and SL.While DMTU?H₂O₂ scavenger?treated did not induce changes in these physiological parameters.When CL was first applied to DMTU and then subjected to wound or exogenous ATP treatment,compared with CL alone on wound or exogenous ATP treatment,the levels of H₂O₂,MDA,CAT and PPO in CL and SL of the former were significantly decreased;When DMTU was applied to the petiole junction or the system and then the CL treated with wound or exogenous ATP,compared with CL alone on wound or exogenous ATP treatment,the MDA,CAT,H₂O₂,PPO levels in CL of the former did not change significantly,the physiological indexes of SL were significantly decreased.These results indicated that the effect of eATP on the wound response of bean depended on the regulation of H₂O₂,and H₂O₂transfer played a role in the regulation of eATP on systemic wound response.?3?The level of eATP was affected by iATP.We used oligomycin?Inhibitors of F₀F₁-ATPase?inhibits the content of iATP in tobacco suspension cells.Oligomycin treatment caused a decrease in the levels of iATP and eATP,which gradually decreased with the increase of the processing time and processing concentration;moreover the level of cell death increased with the increase of oligomycin processing time and processing concentration.Treated with exogenous ATP alleviated the decrease in iATP and the increase in cell death caused by oligomycin.Therefore,the level of eATP can be affected by iATP,and eATP can regulate the iATP production and cell death when mitochondrial ATP synthesis was inhibited.In conclusion,eATP,as an important signal molecule,is affected by intracellular ATP,and regulates the systemic wound response by H₂O₂.Thus,the role of eATP in plant physiological activities is further understood,and it also provides a useful reference for the study of plant resistance and systemic protection.