| Seagrass beds have important ecological functions and values.However,seagrass beds have been severely degraded globally in recent decades,and conservation and restoration studies are urgently needed.At present,seagrass bed restoration methods such as habitat method,transplantation method,and seed method have some limitations.Among them,obtaining seagrass seedlings is the key link to successful seagrass restoration.Generally,tissue culture technology can be used to obtain a large number of seagrass seedlings quickly,but there are problems such as the mechanism of developmental regulation of exosome induction and its suitable culture conditions are not clear.Therefore,in this study,we explored the WOX gene family of Thalassia hemprichii,a common tropical seagrass,which has the function of regulating stem cells and promoting plant growth and development,and analyzed the transcriptomic effects and physiological responses of Thalassia hemprichii under salt stress.The main findings are as follows:(1)Mining the WOX gene family information of Thalassia hemprichii,we screened and obtained one WOX gene,and named it Th WOX8,and found that Thalassia hemprichii was more closely related to Fabaceae Lindl.and Nelumbo nucifera Gaertn.by homology comparison and evolutionary tree analysis,and Thalassia hemprichii transcription factors were more closely related to only one aquatic plant,Nelumbo nucifera Gaertn..(2)The physiological response and changes in some physiological indicators of Thalassia hemprichii under different salinity stress were also investigated under laboratory conditions.The physiological changes were mainly in leaf abscission and high mortality rate under high or low salt stress,and the physiological indexes were mainly in leaf soluble protein content,which showed a decreasing trend from 0 to 12 h and a significant increase from 12 to 24 h,soluble sugar content,which was increasing from 48 h,and MDA content,which increased from 0 to 12 h in the initial stage and started to decline after 24 h.The content of malondialdehyde increased from 0 to 12 h at the initial stage and began to decline after 24 h.The decline was fastest in high salt stress(salinity 45).(3)Analysis of the early expression patterns of Thalassia hemprichii subjected to different concentrations of salt stress showed that the expression patterns differed greatly under different concentrations of salt stress,specifically,the gene expression patterns of Thalassia hemprichii under the influence of high salt stress(salinity 45)were more numerous and varied more strongly,meanwhile,the number of up-regulated genes was significantly more than the down-regulated genes in both high and low salt stresses.Analysis of these differentially expressed genes revealed that the co-expressed genes were completely different in the three salinity treatment groups,but most of the genes were associated with salt stress,indicating that the gene expression patterns were completely different under different salt concentration treatments.(4)A study of differentially expressed genes in Thalassia hemprichii subjected to different concentrations of salt stress revealed that the overall number of differentially expressed genes was small and there were no genes co-expressed under different salinity treatments at different time points.The 319 differentially expressed genes at each time point were enriched for KEGG and GO,and it was found that these genes were mainly enriched in transport and catabolic,environmental adaptation pathways.In this study,we not only discovered the existence and explored the function of WOX gene of Thalassia hemprichii,but also preliminarily explored some salt tolerance mechanisms and suitable salinity conditions for tissue culture of Thalassia hemprichii,which provides theoretical and technical support for the subsequent selection of suitable conditions for seagrass tissue culture and is of great significance for the research of seagrass ecological conservation and restoration. |
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