The Study On The Effects Of EATP And AOX On The Regulation Of Plant Photosystem ?

Adenosine 5'-triphosphate?ATP?acts as a direct energy donor in the majority of cells,such as animals,plants and microorganisms.And,when ATP is released into extracellular matrix,extracellular ATP?eATP?acts as a signal molecule to stimulate intracellular important second messengers(such as Ca²⁺,H₂O₂,and NO)in cell signal transductions and thus regulates a number of physiological processes.Alternative oxidase?AOX?,also known as the cyanide resistant oxidase,is a terminal oxidase located in the inner mitochondrial membrane of plant cells,which catalyzes the alternative respiration pathway.The alternative respiration pathway can decrease the ROS accumulation and avoid oxidative damage.In this experiment,‘nong pu'12 bean?Phaseolus vulgaris L?leaves were used to study on the effects of eATP and AOX on the regulation of plant photosystem ?,the main findings are as follows:?1?Extracellular ATP can alleviate the effects of NaCl stress on photosystem ? in plants.In higher concentration,NaCl could cause the decrease of the photochemical efficiency of bean leaves and increase of dissipation of light energy.The application of exogenous ATP effectively mitigated the decreases of the photochemical efficiency of photosystem ? when plants were subjected to NaCl stress.?2?Alternative oxidase regulate the systemic responses of plants to the to high light stress.Exposure of parts of leaves to high light caused the decrease of the photosystem ? and photoinhibition,seriously permanent damage,and this aslo resulted in the responses of systemic leaves to this stress.Using inhibitors to inhibit alternate respiration pathways,the results showed that the systemic response of leaves to high light could be regulated by alternate oxidase..?3?There is some relationship between eATP and the alternative respiration pathway in regulation of responses to high light stress.eATP,as an important extracellular signal molecule,participates in the regulation of the photochemical efficiency of photosystem ? under high light.And AOX was also involved in the regulation of the photochemical efficiency of photosystem ? in light stress.Thus,in this paper,we investigated whether there is association between eATP and AOX on PS? regulation under high light stress.Trough using alternative oxidase inhibitor?SHAM?t,the results showed that SHAM inhibited the regulation of PS? by eATP under light stress,and indicate the regulation of eATP on PS? may be related to alternative oxidase under high light.In conclusion,eATP and AOX play important roles in regulating plant PS?,and there is some relationship between them.