Study On Salt Tolerance Mechanism In Zoysia Macrostachya

Zoysia macrostachya is a perennial grass of gramineae,which has a strong salt-tolerance.Little attention has been paid to Zoysia macrostachya at home and abroad.Most of the studies on Zoysia macrostachya focused on the physiological mechanism of seed germination and salt-tolerance of seedlings,but almost no further molecular studies were involved.Zoysia macrostachya grows in coastal beach-lands,grass low and thick,high yield,can adapt to the bad ecological environment of the beach,but the utilization rate is very low.At present,land salinization is very serious worldwide,which has become a global environmental problem.Using biological measures to plant salt-tolerant plants on saline-alkali land can not only improve the salinization of land,but also produce certain economic benefits.However,we do not fully understand the molecular mechanism of salt-tolerant plants,and lack of effective salt-tolerant genes,which directly affects the further development of plant salt-tolerant gene engineering technology.Therefore,the salt tolerance mechanism of halophytes should be studied in depth,and relevant genes related to salt tolerance should be screened and excavated.Through genetic engineering and other relevant technologies,the salt tolerance of plants should be improved,and new varieties of plants with more salt tolerance should be cultivated,so as to solve the problem of low utilization rate of saline-alkali land.In order to investigate the molecular mechanism of salt tolerance of Zoysia macrostachya and to screen related genes of salt tolerance,this study took Zoysia macrostachya,a salt-tolerant plant,as the experimental material and conducted transcriptome sequencing analysis on the leaf slices of Zoysia macrostachya treated with 300mmol/L Na Cl for 24 hours.The research results are as follows:1.According to the change trend analysis of relevant physiological indicators(Soluble sugar content,soluble protein content,proline content,MDA content,chlorophyll content,POD activity,SOD activity,CAT activity and Na~+/K~+),it was found that under the stress of 300mmol/L Na Cl,the response trend with time was significantly different at 0h and 24h after the stress.We determined 0h and 24h salt stress as the conditions for sequence and verification test.2.Sem,paraffin section observation,energy spectrum analysis and net photosynthetic rate determination were performed on the leaves of Zoysia macrostachya in treatment group and control group.The salt glands of Zoysia macrostachya were mainly distributed in the axial plane of the leaves,which were composed of cap cell and basal cell.There was no significant difference in the types of related salt ions in the salt glands between the treatment group and the control group,and the relative Na~+content in the treatment group was higher than that in the control group.This was due to the increase of Na~+content in the culture medium.In order to alleviate the stress effect,the excess salt ions absorbed by roots were discharged to the leaf surface through the salt glands.Due to the limitation of stomatal factors and non-stomatal factors,the net photosynthetic rate of Zoysia macrostachya significantly decreased after salt treatment for 24h.3.Through gene differential expression screening,a total of 8705 unigenes differential expressions were obtained.4904 up-regulated unigenes enriched 276biological processes,such as"gluconeogenesis","ethylene response","gibberellin response"and"jasmonic acid response".3801 down-regulated unigenes enriched211 biological processes,such as"inherent immune response","chloroplast RNA processing","flower development rules"and"chloroplast ribosome RNA processing".Biological processes such as transmembrane transport,gluconeogenesis,hypomycin response and ethylene response were speculated to be related to salt-tolerance of Zoysia macrostachya.