Study On The Molecular Mechanism Of Exogenous Jasmonic Acid Enhancing Wheat Salt Resistance

In this study,wheat"Zhengmai 366"was pretreated with different concentrations of jasmonic acid（0,10,50,100 and 200μM）to study the changes of growth and development and physiological and biochemical indexes of wheat seedlings under 150m M NaCl stress for 1,3 and 5 days.Through determination,it was found that the most effective concentration of exogenous jasmonic acid to alleviate salt stress was 100μmol/L,so we selected CK,NaCl,100μM JA and 100μM JA+NaCl for transcriptome sequencing,We obtained a large number of expression information of genes related to salt stress in wheat seedlings,and further analyzed these differentially expressed genes（DEG）by means of bioinformatics.Through analysis,we obtained some results:salt stress significantly decreased plant height,root length,fresh weight,dry weight,relative water content,chlorophyll content and protein content of wheat seedlings,but significantly increased MDA content,activities of antioxidant enzymes SOD,CAT and APX and antioxidant content of wheat seedlings.Compared with salt stress treatment,jasmonic acid pretreated wheat seedlings significantly increased plant height,root length,fresh weight,dry weight,relative water content,activities of antioxidant enzymes SOD,POD and APX,and significantly decreased MDA content in wheat seedlings.These physiological indexes showed that jasmonic acid could increase the tolerance of wheat seedlings to salt stress.Then the double-terminal transcriptome sequencing of salt-treated wheat seedlings was carried out by using Illumina Hi Seq^TM4000 sequencing platform technology,and the original data of CK,NaCl,JA and JA+NaCl were obtained,which were 36756718,44781028,47240416 and 51309000respectively,and the filtered data were 35593966,43114712,44878396 and 48678204,respectively.Then through transcriptome assembly,gene functional annotation,detection of differentially expressed genes（DEG）and functional analysis of DEG,we found that in the DEGs selected by JA+NaCl and NaCl treatment groups,according to GO functional annotation,we found that differentially expressed genes were in the"biological process"."protein phosphorylation（proteinphos phorylation）","transcriptional regulation,DNA templating（regulation of transcription,DNA-templated）"and"defense response（defense response）"were the most frequently distributed,with 62,50 and 43 respectively.In the"cell component"type,the items with the largest enrichment number were"nuclear（nucleus）","plasma membrane（plasma membrane）"and"cytoplasmic（cytoplasm）",which were 166,143,110respectively,while in the"molecular function"type,there were more genes enriched in"catalytic active（catalytic activity）"and"binding（binding）".Compared with the KEGG database,9124（16.81%）of the 54263 single gene clusters were significantly matched in the database and assigned to 19 KEGG pathways.The most representative pathways are carbohydrate metabolic pathway（1330 members）,translation（1190 members）,folding,classification and degradation（1010 members）and environmental adaptation（996 members）.Through GO analysis and KEGG functional annotation,we found that the expression of genes related to salt stress in wheat was more active in plant hormone signal transduction,amino sugar and ribose metabolism,phenylpropanoid biosynthesis,carbon metabolism,amino acid biosynthesis and photosynthetic carbon sequestration.To sum up,the morphological structure and physiological and biochemical functions of wheat seedlings were significantly inhibited under salt stress,and JA pretreatment could effectively alleviate the damage of wheat seedlings caused by salt stress,and effectively resist the damage caused by salt stress by promoting the production of antioxidant enzymes and osmotic stress substances and activating the expression of genes related to salt stress,so as to improve the salt tolerance of wheat.And we analyzed the differentially expressed genes related to salt tolerance in wheat seedlings pretreated with jasmonic acid at the transcriptional level,and analyzed the biological functions of related genes in response to salt stress in wheat under jasmonic acid pretreatment.the molecular mechanism of jasmonic acid pretreatment in improving salt tolerance of wheat was further revealed in order to widely apply trace jasmonic acid to improve plant salt tolerance.Furthermore,it provides a scientific and theoretical basis for improving the quality and yield of crops.