Regulation Effect Of Extracellular ATP On Physiological Responses Induced By Chitosan

5'-adenosine triphosphate(ATP)can be released from the inside of the cell to the outside of the cell to form extracellular ATP(eATP).As a signal molecule,extracellular ATP participates in the regulation of plant growth and development,cell metabolism and defense responses through specific signal transduction mechanisms.In this paper,tobacco suspension cells were used as experimental materials to study the effects of extracellular ATP on chitosan-induced ROS levels and PAL activity changes.Arabidopsis plants were used as experimental materials to study the effects of extracellular ATP on chitosan-induced the influence of ROS level,stomata opening and chlorophyll fluorescence parameters.The main results of this paper are as follows:(1)Tobacco suspension cells were used as experimental materials,we found that the tobacco suspension cells mixed with chitosan 5-20?g·m L^-1 increased the intracellular ROS level at adose-dependent manner,and the PAL activity also increased and reached to the maximum at 15?g·m L^-1chitosan,and then decreased slightly.There was not significant difference in ROS levels and PAL activity in tobacco suspension cells by adding 10-40?mol·L^-1 exogenous ATP.The extracellular ATP(eATP)level gradually decreased with the concentration of chitosan increased.The effects of eATP on the chitosan-induced change of ROS level and PAL activity were further analyzed.The results showed that the exogenous ATP 20?mol·L^-1 added to chitosan-induced tobacco suspension cells effectively alleviated the increases of ROS level and PAL activity in cells.These results showed that effects of extracellular ATP can affect the chitosan-induced changes in ROS level and PAL activity in cells.(2)Wild type(Col-0)and dorn1-3 mutant Arabidopsis plants were used as experimental materials.It was found that extracellular ATP could regulate the changes of ROS level,stomatal opening and chlorophyll fluorescence parameters induced by chitosan in Arabidopsis leaves.100?g·m L^-1 chitosan treatment significantly increased ROS levels in wild-type and mutant Arabidopsis plants,and the increase of ROS level in wild-type was higher than that in mutant Arabidopsis plants.Chitosan treatment also induced stomatal closure in leaves of wild-type Arabidopsis,but mutant Arabidopsis was not sensitive to chitosan treatment.Under the treatment of lower concentration of chitosan(25-50?g·m L^-1),the photochemical level of wild-type Arabidopsis PS?increased.Compared with the wild type,the photochemical level of PS?in the mutant Arabidopsis leaves has a greater increase.The higher concentration of chitosan reduces the photochemical level of Arabidopsis.It shows that the production of ROS,the closing of stomata and the change of photochemical level of PS?in leaves caused by chitosan are regulated by extracellular ATP.In conclusion,extracellular ATP plays a regulatory role in some physiological reactions induced by chitosan.This study provides us with a further understanding of the physiological functions of chitosan and extracellular ATP.