Study On Physiology And Transcriptional Of Salix Linearistipulars Leaves In Response To Na₂CO₃ Stress

Salix linearistipularis has strong saline-alkali tolerance,and is considered as excellent halophytic woody plants materials for studying the molecular mechanism of saline-alkali tolerance.However,the genetic background of S.linearistipularis is complex and its genome has not yet been published,which has brought many difficulties in studying the molecular mechanism of saline-alkali tolerance.In order to further explore the molecular mechanism of saline-alkali tolerance of S.linearistipularis,this study used S.linearistipularis seedlings of the same parent as experimental materials to conduct physiological and transcriptomic studies on the leaves of S.linearistipularis after Na₂CO₃ stress treatment,explore the genes that respond to saline-alkali stress in S.linearistipularis and preliminarily analyze their functions.The main research results are as follows:1.The culture of sterile cutting seedlings of the same parent of S.linearistipularis showed that the most suitable medium was MS medium added with plant gel,and the cutting position suitable for mass propagation is the lateral bud.After soil culture and transplanting,the seedlings of S.linearistipularis aged 45-50 days can tolerate 150 m M Na₂CO₃.2.Physiological analysis showed that after Na₂CO₃ stress treatment,MDA,soluble sugar,and proline in leaves continuously accumulated,indicating that alkali stress damaged the integrity of leaf cell membrane;most of the antioxidant enzymes in the ROS scavenging system were activated,especially the activities of SOD,GPX,and GR were significantly increased,indicating that the ROS scavenging system may play an important role in the response of S.linearistipularis to Na₂CO₃stress.3.A total of 32295 DEGs were identified by transcriptome analysis,which were divided into 8 Clusters according to their expression patterns;enrichment analysis of GO and KEGG showed that the metabolic activity in S.linearistipularis after Na₂CO₃may be relatively active,and lipoxygenase（LOX）and JA biosynthesis pathway may play an important role in this process.4.At LOX6 mainly plays a role in wound induced JA formation and participates in regulating stomatal movement of guard cells in A.thaliana.The At LOX6 homologous gene Sl LOX6 in S.linearistipularis is downregulated after Na₂CO₃ stress.Therefore,we cloned the ORF region of the gene and preliminarily analyzed its function.The results showed that the Sl LOX6 gene encodes 926 amino acids and has the closest relationship with the LOX system of Populus tricocarpa and Populus alba.It has tissue specific expression,and the expression in the stems and leaves of S.linearistipularis is significantly higher than that in other tissues.Transgenic Sl LOX6 gene reduced the tolerance of yeast strains to stress,which suggests that S.linearistipularis may reduce the degree and speed of its own aging by reducing the expression of Sl LOX6 gene,enhance its own anti aging ability,and thereby improve its ability to respond to stress.These results provide important information for further understanding the salt tolerance mechanism of the halophytic woody plant S.linearistipularis.