The Analysis Of Transcriptional Regulatory Response To Salt Stress And AQP Family Function In Melilotus Albus

Melilotus albus is annual or biennial legumes,with strong salt tolerance and high crude protein content.At present,the research on the salt tolerance mechanism of M.albus is mainly focused on its morphology,physiology and seed germination.There are few studies on the molecular mechanism of salt tolerance.Long non-coding RNAs（lncRNAs）participate in plant abiotic stress response by regulating gene expression.In this study,transcriptome sequencing was used to explore the roles of lncRNA and mRNA in response to salt stress in M.albus.The lncRNA（MSTRG.50852.2）and aquaporin（AQP）related to salt stress were preliminarily identified.The main results are as follows:1.Genome-wide analysis of the lncRNA and mRNA expression characteristics were performed in M.albus under salt stress.High-throughput sequencing was performed on 18 samples of M.albus under salt stress,and a total of 9437 lncRNAs were identified.550 and 8273 differentially expressed lncRNAs（DELs）and mRNAs（DEGs）in response to salt stress were identified,respectively.The lncRNAs were more tissue-specific in response to salt stress.545（99.1%）DELs were predicted to regulate6616（80.0%）DEGs in cis,trans and miRNA-mediated ways.The target genes of DEL were related to oxidation-reduction process,carbon metabolism and amino acid biosynthesis pathways.The competitive endogenous RNA（ceRNA）network contained99 miRNA,67 lncRNA,and 128 mRNA.qPCR and dual-luciferase（LUC）assays demonstrated that MSTRG.50852.2 might participate in salt stress response by regulate the expression of WD40 gene（EVM0029402）by competitively binding mtr-miR7696a-3p in M.albus.2.The AQP genes were genome-wide identified in M.albus.A total of 44 AQP genes（MaAQP）were identified from M.albus genome.The phylogenetic tree divided them into five subfamilies: PIP,TIP,NIP,SIP and XIP.Promoter cis-acting element analysis,transcriptome data and qPCR experiments indicated that MaAQP gene might be involved in plant growth and development,abiotic stress and abscisic acid（ABA）response.Yeast heterologous expression experiments showed that overexpression of MaPIP2;1,MaTIP2;2 and MaPIP1;1 gene could improve the salt tolerance of yeast cells.These three genes might be involved in maintaining water homeostasis in M.albus under salt stress.