Study On Physiology And Proteomics Of Salix Linearistipularis Leaves In Response To Na₂CO₃ Stress

Soil salinity is a major environmental limiting factor that adversely affects plant growth and development.The contents of alkaline salts(e.g.Na2CO3 and NaHCO3)are high in saline-alkali soil of Songnen Plain in northeast China.Alkaline salt not only brings ionic stress to plants,but also causes high pH damage,which is more serious than NaCl.Salix linearistipulars are the only woody plant with community distribution in saline-alkali region,which has strong adaptability.Thus,S.linearistipulars are considered as excellent halophytic woody plant materials for understanding the molecular mechanism of alkali response.Therefore,it is very important to explore molecular mechanisms of alkali response in S.linearistipulars.In this study,we have studied the response mechanism of Na2CO3 stress in the leaves of S.linearistipulars by physiological and proteomic methods.The results showed that Na2CO3 broke the integrity of the membrane structure and increase the content of malondialdehyde.In addition,the osmotic protective substances(e.g.,soluble sugar,proline,and glycine betanine)were accumulated,the activities of antioxidant enzymes were changed significantly,such as peroxidase,ascorbate peroxidase,dehydroascorbate reductase,glutathione peroxidase and glutathione reductase.Proteomics studies found 154 differential proteins.Among them,the abundances of 109 proteins were increased,and 45 proteins were decreased.These proteins were mainly involved in signaling transduction,membrane and transport,ROS homeostasis,stress and defense,transcription and DNA replication,protein fate,energy metabolism,basal metabolism,secondary metabolism,nucleotide metabolism,cell wall metabolism,photosynthesis,miscellaneous and function unknown.Our results indicated that S.linearistipulars applied several strategies to cope with Na2CO3 stress,which includes:sensing the stress by regulating signal transduction-related proteins,maintaining osmotic balance through the accumulation of osmotic protective substances;adjusting the heat shock protein and molecular chaperone,regulation of the abundances of key enzymes that participate in glycolytic process,TCA cycle and basal metabolic pathways.These results provide an important theoretical basis for revealing the alkaline salt stress-response mechanism in leaves of S.linearistipulars.