Dynamic Response Of LncRNAs To Salt Stress For Populus Euphratica

Long honcoding RNAS(lncRNAs),i.e.,Tong RNA transcripts that not encode protems,are believed to play regulatory roles in mediating plants’ response to biotic and abiotic stress.Soil salinity is one of the most important abiotic stresses.So for,there are few studies on the roles of IncRNAs in salt tolerance mechanism for woody species.Salt-tolerant Euphrates poplar(Populus euphratica)was used as experimental material in this study.Dynamic transcriptome data were obtained from P.euphratica seedings under salt stress at multiple time points using high-throughput strand-specific RNA sequencing.By mapping to the reference genome,P.euphratica IncRNAs were identified at the whole genome-wide level.The dynamic gene regulatory networks between IncRNAs and their target genes,between mRNAs and mRNAs were reconstructed.Based on the patterns of gene expression,network topology and function annotation information,the roles of IncRNAs and mRNAs in response to salt stress in P.euphratica were studied.The main results of this paper were given as follows:(1)P.euphratica IncRNAs were for the first time identified at a genome-wide level by the high-throughput sequencing technology.A total of 36,075 IncRNAs were identified.By structure and expression analysis,it was found that P.euphratica lncRNAs had similar characteristics to those in other species.It was also found that P.euphratica lncRNAs were evenly distributed along the genome.Additionally,60 IncRNAs were observed to be targeted by miRNAs and 53 lncRNAs observed to function as eTMs of miRNAs.(2)A total of 555 differentially expressed IncRNAs under salt stress were obtained.GO enrichment analysis of their differentially expressed target genes was enriched in the process of "trehalose biosynthesis","amino acid transmembrane transport","ABA-mediated signaling pathway","DNA-dependent transcriptional regulation","oxidation-reduction reaction",etc.The salt-responsive lncRNAs were divided into 13 distinct clusters and GO enrichment analysis in each cluster showed that the clusters associated with the transient response had different biological characteristics with those associated with the persistent response.The complex regulatory networks between IncRNAs and their target genes were reconstructed in each cluster.Finally 54 key salt-responsive lncRNAs were identified,including 22 lncRNAs associated with the transient salt stress response and 32 lncRNAs associated with the persistent salt stress response(3)The response of plant to salt stress is a complex biological process.In addition to lncRNAs,the expression of mRNAs is also altered under salt stress.This study also provided mRNA population under salt stress in P.euphratica.A total of 1,819 mRNAs were identified to be differentially expressed under salt stres.These salt-responsive mRNAs were divided into 28 clusters.These genes assigned to the transient response clusters were found to be involved in the "jasmonic acid signal pathway","mannose synthesis","trehalose synthesis","disaccharide synthesis","regulation of hydrolase activity",etc.While those genes assigned to the persistent response clusters were involved in the "cell wall macromolecules metabolic process" and "cell wall composition and biogenesis".Then the complicated gene regulatory networks in each cluster were reconstructed.Finally the "core" genes in P.euphratica related to the transient and persistent salt stress response were identifiedThis study capitalized on time-series experiments to characterize both transient and persistent salt stress responses,profiling the dynamic expression changes of lncRNAs and mRNAs under salt stress The results for this study provide a potential direction for subsequent research such as gene cloning,functional identification and transgenic breeding.