Physiological And Proteomic Analysis Of Puccinellia Tenuiflora In Response To NaHCO₃

Saline-alkali is a major abiotic stress that limits plant growth and productivity.NaHCO3 is one of the vital saline-alkali treatment,which gives ion stress and additional pH stress to plants.Puccinellia tenuiflora is a halophytic plant widely distributed in the saline-alkali soil of the Songnen Plain in Northeast China,This NaHCO3-tolerant mechanisms is vitral towards improving saline-alkali soil.In this study,the NaHC03-responsive molecular mechanisms in P.tenuiflora were investigated using combined morphology physiological and proteomics approaches.The plant growth was inhabited,such as lower relatively water content,shorter shoot length,and less fresh and dry weight under NaHCO3 treatment.In addition,comparative proteomic analysis revealed 90 identities(representing 77 unique proteins)differentially expressed in P.tenuiflora leaves under NaHCO3 treatment.These proteins were mainly involved in photosynthesis,carbohydrate and energy metabolism,protein metabolism,stress and defense,transcription and protein turnover.Those protein abundant changes and relative phosiology results indicated the following NaHC03-responsive mechanisms:(1)Decreased abundance of proteins involved in Calvin cycle led to reduced photosynthesis activity,including RuBisCO LSU,RBP and PRK,(2)Accumulation of Na+causes ion stress and dissipates the membrane potential.The remarkable increased result of malondialdehyde(MDA)and relative electrolyte leakage further illustrated the increase of membrane lipid peroxidation and membrane permeability.Moreover,the accumulation of proline,soluble sugar,and betaine enhance the ability of osmotic regulation are helpful to preserve the integrity of cell structure.Furthermore,K+uptake and the accumulation of compatible solutes are vital strategy in modulating ion,osmotic and pH homeostasis.(3)Reactive oxygen species(ROS)scavenging constitutes an important mechanism.Interestingly,the antioxidative enzymes showed diversity to regulate the cellular redox state and defend against the oxidative stress.The activities of SOD,POD,CAT,and GPX were significantly increased under NaHCO3 treatment.Importantly,the activities of enzymes in ascorbate-glutathione cycle showed diverse patterns with the increase of NaHCO3 concentration.The activities of APX,MDHAR,DHAR,and GR were all increased under 150 mM NaHCO3,while the activities of APX,MDHAR,and GR were enhanced under 400 mM NaHCO3,but only GR activity was induced under 800 mM NaHC03.In addition,the induced activity and abundance of GST,as well as increased GLO,were all contributed to defend against the oxidative stress caused by NaHC03 and maintain the balance of GSH and GSSG.(4)Protein synthesis,processing,and turnover are essential for NaHCO3 response.Our data demonstrate that proteome and physiological changes enable saline-alkali tolerance in P.tenuiflora and consequently a positive impact on plant productivity.