Germplasm Resources Analysis And Character Improvement Of Medicago Sativa Under Drought And Salt Stress

Medicago sativa L.is a kind of perennial legumes with high nutritional value and good palatability.In the cultivation of alfalfa,drought and salt stress have a great effect on the growth of alfalfa.In this experiment,15 alfalfa materials were selected,including 11 foreign materials and 4 domestic materials.Most of the materials are local varieties,farm varieties or ecological types.The 15 alfalfa materials used for agronomic character determination were used to determine agronomic character.Salt tolerance evaluation and genetic diversity analysis were conducted.Germination rate,germination potential,radicle length,germ length and seedling dry weight were measured at germination stage.The results showed that stem diameter was the most correlated with yield,followed by plant height,and the correlation coefficients were 0.39 and 0.30,respectively.A total of 565 alleles were detected for SSR markers,and 18.83 alleles were amplified on average for each locus.The polymorphism information content(PIC)was 0.84,and the polymorphism information content of the selected SSR markers was above 0.6.The number of alleles and PIC had little relation with the number of markers,but had close relation with their polymorphism.In the aspect of salt tolerance identification,the root length and germination index were the most closely correlated among the indexes of seed germination stage,and the correlation coefficient was 0.931.The correlation degree of salt tolerance of all indexes ranged from 0.353-0.793,among which the dry weight and germination rate of seedlings were closely related to the salt tolerance of varieties.The drought related gene MsZNR was screened out through genome sequencing results,and the MsZNR gene was amplified.Transgenic alfalfa plants were obtained through plant tissue culture.Physiological and biochemical indexes in the transgenic alfalfa plants detection,endogenous hormone level analysis,subcellular localization,the transcriptome sequencing and analysis,related gene expression analysis,explore the transgenic alfalfa plants under drought stress condition associated with wild-type plants gene,hormone levels,and the difference of physiological and biochemical,explore MsZNR gene of alfalfa drought stress regulation effect,and provide new perspectives for alfalfa drought response mechanism.The results showed that under drought conditions,the content of malondialdehyde and proline in transgenic plants was significantly lower than that in wild-type plants,while abscisic acid was significantly increased in transgenic plants,auxin,cytocytotin and gibberellin showed an opposite trend,but the change of ethylene concentration was not significant.qRT-PCR analysis of APX,POD and SOD genes showed that the expression level of APX gene was significantly higher than that of wild type,while the expression level of POD gene and SOD gene was significantly lower in transgenic plants.On alfalfa MsZNR gene function and regulation mechanism under adversity stress analysis,further understand the resistance of alfalfa stress response mechanism,to from the molecular level on the behavior of alfalfa varieties improvement and alfalfa strain improvement to provide conditions,so as to lay a foundation for alfalfa growth quality improving,alfalfa strain improvement.