Transcriptomic Analysis On Stress-Resistant Protein Kinase,Transcription Factor And Antioxidant System Of Atriplex Canescens In Response To Salt Treatment

Atriplex canescens?four-wing saltbush?,a C₄ perennial shrub,belongs to the genus Atriplex L.?Chenopodiaceae?.This species is an attractive forage for most livestock due to its strong tillering ability,high nutritional value and evergreen leaves.Besides,it is also an important species for erosion control and vegetation restoration in salinized desert areas on account of its excellent characteristics of drought resistance,salt tolerance and fast growth.Thus,A.canescens contains abundant stress-resistant genetic resources as well as potential utilization value.At present,there are numerous studies on the physiological and ion transport mechanisms of salt tolerance in A.canescens.However,the possible molecular basis related to stress-resistant protein kinase,transcription factor and antioxidant system in A.canescens response to has not been reported.By using RNA-seq sequencing,therefore,this study obtained the transcriptome data of A.canescens under salt treatment and analyzed the differentially expressed genes?DEGs?related to protein kinase,transcription factor and antioxidant system in A.canescens.The major results are as follows:1.A transcriptome sequencing on A.canescen seedlings treated with 100 mmol/L NaCl was performed,and total 70,571 unigenes with an average length of 961 bp were obtained.Then,44,121 unigenes?62.52%of the all-unigenes?were annotated to the known genes in the public databases,including Nr,Nt,Swissprot,KEGG,COG,Interpro and GO.2.Under 100 mmol/L NaCl treatment,a large number of protein kinase encoding genes related to stress response were significantly up-regulated in roots and leaves of A.canescen.After NaCl treatment for 6 h,the expressions of receptor protein kinases?LRK,WAK,LRR?and MAPK/MAPKK/MAPKKK proteinoid kinase genes were significantly up-regulated in leaf and root of A.canescen;Under NaCl treatment for24 h,CDPK,MAPK/MAPKK/MAPKKK and receptor protein kinase related genes showed high expression.These results suggested that the receptor protein kinase,RPK,CDPK and MAP kinase may play the important roles of signal transduction in A.canescen response to the saline conditions.3.After being treated with 100 mmol/L NaCl,HSF,ZF,bHLH,bZIP/HD-Zip,WRKY transcription factor family encoding genes related to stress response in leaf of A.canescen were continuously up-regulated,which was involved in the whole process of response to salt treatment in the leaf of A.canescen.In the early stage of salt treatment?6 h?,the up-regulated expressions of HSF,ZF,MADS-box,bHLH,bZIP and MYB transcriptional factor genes were observed in the roots of A.canescen.In the late stage of salt treatment?24 h?,the NAC,AP2/ERF and WRKY transcriptional factor genes were also significantly up-regulated in addition to the transcription factors induced in the early stage.These results indicated that above transcription factors might play important roles for A.canescen adapting to saline environment.4.Under 100 mmol/L NaCl treatment,a large number of antioxidant enzyme genes in root and leave of A.canescen were significantly up-regulated.The encoding genes of GST,POD,GLP,CAT,PEX,SOD and GPX were significantly up-regulated after 6 h of NaCl treatment and also maintained the expression levels under NaCl treatment for 24 h except that of SOD.Moreover,the genes encoding MDAR,GPX,GLR and TrX antioxidant enzymes were significantly induced in leaf and root treated with NaCl for 24 h.It can be speculated that SOD can be induced rapidly at the initial stage of salt treatment,at the same time,CAT,PrxR/Trx and GPX pathway play an important role in ROS eliminating,while CAT,GPX pathway and ASH-GSH cycle play a key role in eliminating ROS of A.canescen and preventing membrane damage at late stage of NaCl treatment.5.After 6 and 24 hours of 100 mmol/L NaCl treatment,the genes of FLS,CHI,CHS,4CL,C4H and PAL,which related to the synthesis of flavonoids in A.canescen leaves were significantly up-regulated.Moreover,CHS,F3H,C4H,FLS and DFR genes were significantly induced in roots.These results showed that under salt treatment,A.canescen might increase the synthesis of flavonoids by enhancing the phenylpropane pathway and the biosynthesis of flavanones,flavonols and dihydroflavonols.