Physiological And Proteomic Analysis Of Populus Simonii × P.nigra Leaves In Response To NaCl

The alkali-salinity is one of the most significant abiotic stresses factors and it limits the productivity and geographical distribution of plants.The alkali-salinity stress imposed severe effects on a plant by causing water deficit,which subsequently reduce the stomatal conductance,break the balance of osmotic and oxidative homeostasis.Photosynthesis is inhibited,such as the reduction of light energy utility and CO2 assimilation in plants.Populus simonii× P.nigra is a high value plant,as it has an ability to grow well in salinity soil.In this study,the NaCl responsive molecular mechanisms in P.simoniix P.nigra leaf was investigated by using a combined physiological and proteomics approach.We found that the cell integrity was destroyed,molecules that play osmotic protective roles,had been increased,and defense-related enzymes were also affected by NaCl stress after 3 d in the leaf of P.simoniix P.nigra.In addition,we obtained 78 differentially abundant protein spots by using two-dimensional electrophoresis(2-DE)approach.We found that there were 50 spots’ vol%increased and 28 spots’ vol%decreased under NaCl.These proteins were mainly involved in the formation of light harvesting complex,photosystem Ⅱ,photosynthetic electron transfer chain,energy metabolism,Calvin cycle,metabolism,stress and defense,transcription and translation,protein fate,as well as signaling transduction.Taken together of our physiological and proteomics results reveal that P.simoniix P.nigra leaf may utilize various strategies to cope with NaCl treatment.They include:(1)reduce excessive light energy absorption by decreasing chlorophyll content and inhibiting chlorophyll a/b binding protein’s vol%;(2)enhance the heat dissipation by increasing photochemical quenching,and thereby reduce the damage photosynthetic apparatus caused by excessive light energy;(3)minimize the oxidative injury by elevating the specific antioxidant system.In addition,the considerable accumulation of proline and soluble sugar can alleviate osmotic stress,as well as scavenge reactive oxygen.This study lays a solid foundation for further research on salt-tolerant mechanisms in the P.simonii× P.nigra.