Establishment Of Evaluation Method For Salt Tolerance Of Sorghum And Analysis Of Expression Pattern Of SbGABA-Ts Genes Of Sorghum Under Salt Stress

Soil salinization is one of the major environmental pressures that constrain global agricultural development.As the fifth largest crop in the world,sorghum has multiple resistances such as drought resistance,cold resistance,salt and alkali resistance.However,the salt tolerance of sorghum is significantly different among different germplasm,development period and growth conditions,therefore,it is urgent to establish an accurate,systematic and efficient salt tolerance identification system for evaluation and screen sorghum salt tolerant germplasm.The foundation of sorghum salt tolerance mechanism research and germplasm innovation is laid.The Gammaaminobutyric acid(GABA)metabolic pathway is a branch of the tricarboxylic acid cycle.The research results show that this branch can improve plant stress resistance by regulating the acidbase balance and osmotic balance in plants.GABA-T gene is involved in GABA degradation.This gene is related to plant growth and development and response to stress,but there are few reports on this gene in sorghum.In this study,the determination indexes of two growth conditions(germination and seedling stages)and different growth conditions(field and laboratory)were analyzed by various analytical methods to determine the salt-tolerant and salt-sensitive materials,at the same time,the expression patterns of different resistant materials SbGABA-Ts under salt stress are analyzed.The main conclusions are as follows:1.The 200 mmol·L-1 NaCl was determined as the optimal screening concentration in the germination period by comparing the effects of different salt concentrations(0,75 mmol·L-1,100 mmol·L-1,200 mmol·L1)on the germination of different sorghum materials.Using the subordinate function method of relative germination rate and relative germination potential,the salt tolerance of 64 sorghum materials under the stress of 200 mmol·L-1 NaCl was screened.S02,S61,S62,S01,S54 and S09 were relatively salt tolerant accessions;S24,S25,S03,S17 were relatively salt sensitive accessions.The germination rate,germination potential,germination index and relative salt damage rate can be used to screen the salt tolerance of sorghum during germination.2.Principal component analysis,cluster analysis and subordinate function method were used to analyze the plant height,stem diameter,malondialdehyde and proline indexes of 13 sorghum accessions(36 accessions with different salt tolerance at germination stage were screened by field seedling stage)in field and laboratory seedling stage.Salt-tolerant accessions in the field seedling stage:S45,S23,S07,salt-sensitive accessions are S46,S35,S03,S28;Salt-tolerant accessions in the laboratory seedling stage:S23,S30,S41,salt-sensitive accessions are S03,S28,S29.At the same time,it was determined that plant height,proline and superoxide dismutase could be used as screening indicators for salt tolerance in seedling stage.3.In this study,we established a comprehensive salt tolerance identification method based on multilevel phenotypic analysis,namely,different morphological indexes and physiological and biochemical assay indexes were used to systematically and accurately evaluate of salt tolerance of sorghum at different development stages(germination and seedling stages)and different growth conditions(field and laboratory),combined with various data analysis methods.Finally,two salt-tolerant accessions(BSY and Wheatland)and two salt-sensitive accessions(SEM-56-7 and SEM-54-5)were screened out by this method.4.Using fluorescence quantitative detection resistance of different materials,leaf,root SbGABA-Ts gene expression under salt stress,was found in leaf tissue GABA-Ts genes are expressed,presents a kind of phenomenon of circadian rhythm,and salt sensitive material expression quantity higher than that of resistant material,and the roots in the organization is mainly GABA-T2 gene expression,and the expression of leaf and the delta difference instead.In conclusion,there are differences in the expression of SbGABA-Ts gene in different resistant materials and tissues of sorghum.