The Responding Mechanism Of Physiology And Proteomics In Prunus Mira Leaves Under Drought

Drought has been one of the serious abiotic stresses which effects plant growth and development.In order to explore the effects of drought on plant,one year old Prunus mira was used as meterials,which subjected to drought 4,8,12,16 days and rewatering in our study.Physiological,photosynthesis,respiration and proteomics were investigated.Conclusions are listed as follows:In the day 12,a slight wilting,curly and drooping appeared in leaves.With the aggravating of drought,it became more serious.After rewatering,it recovered.In the meantime,leaf water content significantly decreased at day 16,and recovered after rewatering.Drought induced oxidative damage.The content of proline,MDA,H2O2,REC and the productivity of O₂^-significantly increased by drought.Oxidative damage triggered antioxidant system to protect Prunus mira,The levels of SOD,POD,CAT,APX,MDHAR,DAHR,GR and ascorbate activities also significantly increased,meanwhile,the activities of glutathione is suppressed.The content of chlorophyll and carotenoid were increased under drought,but Chla/Chlb decreased,it indicated that drought inhibits the ability of capture of light energy of Prunus mira leaves.At the same time,photosynthesis was restrained by non-stomatal limitation（photosynthesis rate,transpiration rate and stomatal conductance were reduced,intercellular CO2 concentration was increased）.In chlorophyll fluorescence parameters,besides NPQ showed a trend of rising,F_v/F_m,F_v’ /F_m ’,Φ PSⅡ,qP and ETR showed varying degrees of decline.At day 16,the OJIP were lower than control.Under severe drought,the rate of total respiratory and Alt were rise significantly,but Cyt was inhibited.It indicated that Alt plays an important role under drought stress.We found a total of 109 proteins were revealed to be differentially expressed by drought,the identified proteins incorporate a wide range of biological processes,which include: cytoskeleton dynamics（3.67%）,energy metabolism（9.17%）,carbohydrate metabolism（13.76%）,photosynthesis（22.94%）,transcription and translation（4.59%）,transport（1.83%）,defense（30.28%）,molecular chaperones（7.34%）,other materials metabolism（3.67%）and unknown function（2.75%）.These different function proteins were interacted to protect Prunus mira from drought,Among them,the proteins related photosynthesis and defense play particularly important roles in drought tolerance.After rewatering,all these parameters recovered to the normal level or showed a significantly trend of recovered,so we can determine that Prunus mira has a strong drought resistance.