Low Temperature Response Mechanism Of Mitochondrial Membrane Bound Phospholipase D Regulated By Abscisic Acid And Reactive Oxygen Species In Choraspora Bungean

Low temperature is the most common stress factor in environment.Extremely low temperature is harmful to plant's normal growth and development.It has practical significance to research the cold resistance of plant by studing low temperature response.PLD is phospholipid hydrolase in membrane.Exception of PLD function can affect the integrity of the membrane structure and the stability of the function,further damaging the plant cell.So it has important guidance value to research the integrity of the membrane structure,the stability of the function and the resistance of plant by studing the PLD function.Environmental stress can trigger the generation of ABA and ROS.Both ABA and ROS can participate in signal transduction in plant cell.Based on these relationships,we used the low temperature?4?,0?and-4??as stress factor and choraspora bungean as experimental materials to research the effects of ABA and ROS on mitochondrial bound PLD activity in choraspora bungean.Results showed that,?1?The activity of mitochondrial membrane bound PLD increased when choraspora bungean was cultivated under 4?,0?and-4?.When choraspora bungean was treated by 10?mol·L^-1,50?mol·L^-1 and 100?mol·L^-1 ABA under low temperature,the PLD activity was promoted by ABA.When choraspora bungean was treated by 0.3 mmol·L^-1sodium tungstate under low temperature,the PLD activity was inhibited.When choraspora bungean was treated by 0.3 mmol·L^-1 sodium tungstate and 10 mmol·L^-1 CaCl₂ under low temperature,the PLD activity increased.When choraspora bungean was treated by 50?mol·L^-1 ABA and 5 mmol·L^-1 EGTA under low temperature,the activity of PLD decreased.When choraspora bungean was treated by 50?mol?L^-1 ABA under low temperature,the content of mitochondrial membrane Ca²⁺was higher than the the content of mitochondrial membrane Ca²⁺in the control.These results indicated that ABA was able to regulate the PLD activity by Ca²⁺under low temperature in choraspora bungean.?2?The PLD activity was promoted when choraspora bungean was treated by 1mmol·L^-1,5 mmol·L^-1 and 10 mmol·L^-1 H₂O₂ under normal condition.The conten of H₂O₂ increased comparing with the blank control when choraspora bungean was cultivated under low temperature.When choraspora bungean was treated by 12.5?mol·L^-1 DPI under low temperature,the PLD activity decreased,but the content of mitochondrial membrane Ca²⁺increased comparing with the control.When choraspora bungean was treated by 12.5?mol·L^-1 DPI and 10 mmol·L^-1 CaCl₂ under low temperature,the PLD activity increased comparing with the group with single DPI treatment,but the PLD activity decreased when choraspora bungean was treated by 5 mmol·L^-1 EGTA comparing with the control under low temperature.These results indicated that ROS could regulated mitochondrial membrane bound PLD activity by Ca²⁺in choraspora bungean under low temperature.?3?When choraspora bungean was cultivated under 4?,0?and-4?,SOD and CAT activity was higher than the blank control under 4 and-4?.POD activity increased under 4?.APX activity increased during 72 h under 4?and-4?.At the same time,the relative conductivity of membrane increased,but the content of proline and soluble sugar decreased in the control.Under 0?,POD activity decreased in the control,APX activity changed with fluctuation,the content of proline and soluble sugar increased during 72 h and48 h respectively,but the content of soluble protein decreased?After choraspora bungean was treated by 50?mol·L^-1 ABA under low temperature,POD,SOD,CAT and APX activities increased compared with the control.The relative conductivity decreased.proline,soluble sugar and soluble protein content increased.These results indicated that ABA promoted the antioxidase activity,decreased the relative conductivity and inreased the proline,soluble sugar,soluble protein content.