| Leymus chinensis is the main building species and dominant species of typical grassland and meadow grassland in eastern Eurasia.It has strong salt-alkali resistance and has important application prospects in grassland restoration and artificial grassland establishment.In this paper,it setting the pot experiment with saline-alkali stress and the control processing,and saline-alkali solution irrigation stress has used in the growth period of Leymus chinensis.After 30 days of saline-alkali stress,based on the comprehensive analysis results of 13 morphological and physiological indicators,the saline-alkali resistance of 60 Leymus chinensis germplasm resources were evaluated and graded,and under saline-alkali stress,the ultrastructure and three saline-alkali genes(LcBADH2,LcSAIN1,LcOEE1)expression of different saline-alkali resistance of Leymus chinensis germplasm cells were studied.This experiment explains the saline-alkali resistance mechanism of Leymus chinensis from the microscopic level and verifies the accuracy of the saline-alkali resistance classification.It provides a basis for the research on the saline-alkali resistance mechanism of Leymus chinensis and the saline-alkali resistance germplasm screening.Conclusion as below:(1)Saline-alkali stress had significant effects on Leymus chinensis germplasm;there is a certain correlation between different indexes of Leymus chinensis;the sensitivity of each index to saline-alkali stress was different,root dry weight,tiller number and proline content these three indicators have strong correlation with the saline-alkali resistance of Leymus chinensis germplasm,and they can be used as index traits for the study of Leymus chinensis saline-alkali stress;according to the membership function and cluster analysis results,60 Leymus chinensis germplasms will be tested.They are divided into five grades,high salt-alkaline-resistance type(I type,3 species),salt-alkaline-resistance type(type II,22 species),medium saltalkaline-resistance type(type III,22 species),salt-alkaline-sensitive type(type IV,12 species),high salt-alkaline-sensitive type(V type,1 specie).(2)The research resurt of ultrastructural changes of Leymus chinensis leaves,which from high salt-alkaline-resistance type,medium salt-alkaline-resistance type and high salt-alkaline-sensitive type,shows that a series of damaged characteristics of Leymus chinensis leaves cells increased with the increase of saline-alkali stress concentration: the chloroplast morphology is swollen,the thylakoids are swollen,the arrangement is disordered,and the sheet structure is distorted.Compared with the control,the number of steroids increased significantly under different concentrations of saline-alkali stress(P<0.01),and the number and size of starch granules increased first and then decreased.The mitochondria swollen and the internal structure began to be disordered.Under high concentration of saline-alkali stress,the cell wall began to thicken and the wall separation occurred.The change of the ultrastructural damage degree of the three types of Leymus chinensis germplasm cells shows that the judgment of saline-alkali resistance was consistent with the conclusion(1).(3)The relative expression analysis of saline-alkali resistance-related genes(LcBADH2,LcSAIN1,LcOEE1)of 10 Leymus chinensis germplasms with five salinealkali resistance types showed that the relative expression of the three genes increases under saline-alkali stress.The expression levels of the three saline-alkali resistance genes were significantly higher than those of the control group.The relative expression levels of the three saline-alkali resistance genes in high salt-alkaline-resistance type germplasm were higher than those of other germplasms.The relative expression levels of the three saline-alkali resistance genes in high salt-alkaline-sensitive type germplasm were the lowest.The relative expression levels of the remaining genes were basically the same as those of saline-alkali resistance.Under the saline-alkali stress,the relative expression of LcSAIN1 gene was significantly higher than the relative expression of LcBADH2 gene and LcOEE1 gene.The relative expression level of the LcOEE1 gene of the salt-alkaline-resistance type,medium salt-alkaline-resistance type and salt-alkaline-sensitive type germplasms was lower than the control type.The relative expression level of saline-alkali resistance-related gene can be used to judge the saline-alkali resistance of the tested germplasm.The research results are consistent with the comprehensive evaluation of saline-alkali resistance. |
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