Study On Salt Tolerance Identification And Mechanism Of Millet Germplasm Resources

In this paper,55 varieties of millet from different ecological regions were used as materials.Compared with distilled water,NaCl solution was used to simulate salt stress environment.The salt-tolerance of millet germplasm was analyzed and evaluated to select the grain varieties with high salt tolerance.The changes of physiological index of millet germplasm under salt stress were studied to provide the theoretical basis for salt tolerance mechanism of millet.The findings are as follows:1.In the artificial climate incubator,NaCl was used to simulate salt stress to determine salt tolerance and related physiological indexes of 55 millet varieties during germination period.The results showed that: the response of different millet varieties to salt stress was quite different.The bud length,root length,germination potential and germination rate of most of 55 millet materials under different salt stress were smaller than those of the control.Only a few of the materials' buds were longer than those of the control.Fifty-five millet resources were screened for salt tolerance with 1.5% NaCl,of which two were in salt tolerance grade 1,9 were in grade 3,15 in grade 5,16 in grade 7,and 13 in grade 9,11 of the 55 varieties of millet materials had high salt tolerance(salt tolerance grade 3 or above).2.The seedlings with different salt-tolerance in germination stage(seedlings of Lugu 1,Jigu16 and Yugu 1)were used as materials to measure the seedling height,leaf water content,SOD,POD and CAT enzyme changes,as well as proline content and proline synthesis key gene expression.From the point of physiological indexes,the correlation between proline content and SOD,POD and CAT activities of aboveground parts of different types of grain under salt stress was analyzed.It was found that with the prolonging of NaCl stress time,all the seedlings appeared to drop after the first rise trend.The plant height of different millet cultivars was significantly different under different salt concentrations,while the aboveground water content was not significantly different with the increase of salt concentrations.3.In this paper,fluorescence quantitative PCR was used to study the changes of prolinemetabolism related gene expression in the three millet varieties treated with different NaCl concentrations.It turns out,that both SiP5 CR gene and SiP5 CS gene expression were up-regulated,and the increase of the expression of the two genes increased with the increase of salt concentration.In the late stage of salt treatment,the expression quantity of SiP5 CR and Si P5 CS gene of the three millet varieties decreased.This indicates that salt stress promotes the synthesis of proline,and the key gene,SiP5 CR,which regulates the synthesis of proline may play an important role in the accumulation of proline.