Association Analysis On Proteomics And Transcriptomics Of Salt-response In Southern Type Alfalfa Salt-tolerant Mutant

In order to reveal the adaptation mechanism of the southern Alfalfa(Medicago sativa)at the molecular level to the salt stress environment,the proteomics and transcriptomes of the two sample roots of the southern type 'Millennium' salt–tolerant mutants were subjected to normal culture and salt treatment,respectively.Association analysis was conducted to find some potential target proteins that may serve as salt tolerance of Alfalfa.The results of this study are as follows:(1)Using RNA–seq technology,the expression level of 31 815 genes in the root mutants of southern type Alfalfa mutants changed after exposure to 250 mmol/L NaCl for 72 h,among which 5 282 differential genes were detected(2 477 up–regulated and 2 805 down–regulated),including 363 transcription factors belonging to 43 transcription families(125 up–regulated and 238 down–regulated).The significant analysis of GO function showed that differentially expressed genes are widely involved in cellular processes,catalytic activity,metabolic processes,and cellular components.The KEGG Pathway significance enrichment analysis revealed that differentially expressed genes are widely involved in metabolic pathways and biosynthesis of secondary metabolites.Transcription factor analysis revealed that the largest number of response genes was the MYB gene family,followed by the transcription factor family such as AP2–EREBP and MYB–related.(2)Using iTRAQ technology,after exposure to 250 mmol/L NaCl for 72 h,a total of 3 857 quantitative proteins and 747 differential proteins were identified in the root samples of southern type Alfalfa salt–tolerant mutants(370 up–regulated,377 down–regulated).Analysis of the significance of GO function showed that these differentially expressed proteins are mainly involved in catalytic activity,binding,cells,metabolic processes and cellular components.In the COG functional classification,most of the differentially expressed protein functions are concentrated in functional prediction,energy production and conversion,amino acid transport and metabolism,and carbohydrate transport and metabolism.The KEGG Pathway significance enrichment analysis revealed that differentially expressed genes are widely involved in metabolic pathways,biosynthesis of secondary metabolites,biosynthesis of phenylpropanoids,and phenylalanine metabolism.(3)Using the high–throughput multiomics technique,after 250 mmol/L NaCl stress for 72 h,there were 2099 genes and quantitative proteins associated with the salt–tolerant mutants of southern type Alfalfa,and the correlation coefficient was 0.0269.When the trend was reversed,the correlation coefficient of differential protein and gene expression was –0.6653.Under the same trend,the correlation coefficient of differential protein and gene expression was relatively high,being 0.6717.In addition,104 differential proteins with the same differential gene expression trend were identified(70up–regulated and 34 down–regulated).The functions performed by these differential proteins mainly involve the following eight aspects: antioxidants,cell membrane synthesis,signal transduction,protein synthesis,defense,energy production and transport,metabolism,and other and unknown functional proteins.Down–regulated expression of the protein is mainly related to defense,while up–regulated expression of the protein is mainly involved in protein synthesis,antioxidants,signaling and metabolism.In addition,differential proteins such as peroxidase,ferritin,LRR–like receptor kinase,disease–associated protein,and heat shock protein 70 were found in the association,and these proteins may be related to Alfalfa salt stress.