Structural,Physiological Responses And Transcriptome Of Atriplex Patens To Salt Stress

In recent years,the increasing area of land salinization has become a global ecological and environmental problem.More and more attention has been paid to the harm of mixed salt to plants and the mechanism of salt tolerance.In this study,based on the preliminary experiments,the seeds and seedlings of Atriplex patens were subjected to salt stress under controlled conditions and other treatments including exogenous calcium(20 mmol/L Ca(NO3)2,40 mmol/L Ca(NO3)2),calcium inhibitor(400umol/L verapamil,12umol/L ruthenium red)were carried out to explore the effects of calcium on salt tolerance of A.patens,the response characteristics of anatomical structure,physiological indexes and transcriptome of A.patens to salt stress were explored.The salt tolerance mechanism of A.patens and the role of calcium oxalate crystal and calcium in plant salt tolerance were analyzed.According to the test,the following conclusions are drawn:1.The anatomic structure research shows that:Under salt stress,the structure of stem and leaf of A.patens changed in accordance with the environment.Salt stress increased the thickness of the outer tangential wall and cuticle of the stem and leaf epidermis.At the same time,salt stress also led to the increase of leaf thickness,stomatal number and chloroplast number in palisade tissue.The number of cells in stem cortex increased,the number of pith and pith ray increased first and then decreased with treatment time,the number of calcium oxalate crystals in basic tissue increased,and the diameter of xylem vessel was larger.Exogenous calcium and calcium inhibitors can affect the structure of stems and leaves by regulating crystal synthesis and other metabolic pathways,and make A.patens produce structural adaptive changes to salt stress.It was found that the effect of ruthenium red was more lasting than verapamil.This has a certain guiding significance for guiding agricultural production.2.The physiological characteristics show that:(1)Seed germination of A.patens Salt stress could inhibit seed germination and significantly reduce germination rate,germination index and germination potential(P<0.05).The effects of different concentrations of Ca(NO3)2 on salt tolerance of A.patens were different.High concentrations of Ca(NO3)2 inhibited seed germination.Ruthenium red,a calcium inhibitor,could significantly reduce the germination rate(P <0.05),and significantly increase the germination potential and germination index(P <0.05).Verapamil could promote the above three indexes.Under salt stress,exogenous calcium and calcium inhibitors can improve germination rate,germination potential and germination index in varying degrees,which can alleviate salt stress.(2)Plant growth of A.patensSalt stress could reduce plant height,increase leaf length,chlorophyll,water content,biomass,biomass of roots,stems and leaves,and decrease MDA content.However,MDA content of treatment groups and control groups increased with time,showing a similar trend of slight increase in the second week compared with the first week and the third week compared with the second week.Under salt stress,exogenous calcium and calcium inhibitors showed adaptive changes to the above measurement indexes at different stages,such as plant height growth,leaf length,chlorophyll,water content,MDA content and various biomass reduction.These results suggest that the changes of anatomical structure of A.patens under salt stress may be related to the changes of above physiological indexes.3.Transcriptome analysis showed that:Based on the genomic analysis of salt tolerance of A.patens leaves,62.14 Gb clean data were obtained from water control group,mixed salt group and verapamil treated A.patens leaves,and 24389 unigenes with annotation information were obtained.Through the enrichment analysis of differentially expressed unigene,the results showed that unigene in A.patens participated in the response of A.patens to salt stress by regulating photosynthesis pathway,signal transduction mechanism,post-translational modification,protein conversion and other ways.The up regulation of more genes related to photosynthetic antenna proteins is an important adaptive ability of leaf transcriptome of A.patens to salt stress.The salt tolerance of A.patens is related to calcium oxalate crystal.The salt tolerance of plants is a complex process closely related to structure,physiology and gene expression.