Transcriptome Analysis Of Salt-tolerant Maize And The Function And Regulatory Mechanism Of ZmERF98 Gene In Response To Salt Stress

Soil salinization seriously affects the growth of crops.Maize is a kind of saltsensitive crop.Excavating the regulatory factors associated with maize salt-tolerance can not only provide a reference for the analysis of salt tolerance mechanism,but also provide assistance for the cultivation and germplasm improvement of salt-tolerant maize varieties.Materials come from the two types of salt-tolerant maize inbred lines ST1(salt tolerance 1)and SS1(salt sensitive 1)that identified in the early stage.This experiment studied the function and regulation mechanism of maize transcriptome and ZmERF98 responding to salt stress,by using transcriptome sequencing,gene function analysis and interaction mechanism analysis.Major experimental results are as follows:1.Taking young steams of ST1 and SS1 under normal growth and salt treatment as samples to perform transcriptome sequencing.In SS1,salt stress induced differential expression of 1401 genes(513 up-regulated,888 down-regulated).In ST1,salt stress induced differential expression of 1027 genes(295 up-regulated,732 down-regulated).GO(Gene Ontology)analysis and KEGG(Kyoto Encyclopedia of Genes Genomes)analysis showed that differentially expressed genes were enriched in the response to abiotic stimulus(GO:0009628).As compare with that normal growth condition,genes associated with Na+/K+equilibrium and ROS(reactive oxygen species)elimination were expressed differently in salt-sensitive inbred line SS1 and salt-tolerant inbred line ST1 after salt treatment.Differentially expressed genes includes H+ATPase involves in excreting Na+from roots,HKT involves in uploading Na+from xylem,NHX involves In limiting Na+ in vacuoles,HAK involves in transporting K+,CAT involves in eliminating ROS.2.The above differentially expressed genes enriched in abiotic stress response pathways were analyzed,and only the ZmERF98 gene showed opposite expression patterns between SS1 and ST1 inbred lines(ZmERF98 was upregulated in SS1 and downregulated in ST1 under salt treatment),and qRT-PCR further verified the expression of ZmERF98 in normal growth and salt treatment SS1 and ST1.ZmERF98 exhibits tissue specific expression,with the highest expression in maize leaves.The expression of ZmERF98 gene was induced by salt stress.ZmERF98 is located in the nucleus.Compared with transgenic receptors,overexpressing ZmERF98 transgenic lines are sensitive to salt stress,with a decrease in fresh weight percentage and an increase in the expression of ROS scavenging gene ZmCatB.3.There were 260 differentially expressed genes jointly detected in SS1 and ST1.Among them,there are 34 differentially expressed genes that exhibit opposite expression patterns between SS1 and ST1 inbred lines.In order to explore the binding target of ZmERF98,the cis of these 34 differentially expressed genes detected in SS1 and ST1 were further analyzed.The results showed that the promoter region of the differentially expressed gene EXORDIUM with opposite expression patterns contained ZmERF98-bound elements:the EXORDIUM promoter contained ZmERF98-bound elements(GCC-box,CE1 motif:TGCCACCGG).Using yeast one hybrid technology to study the regulatory factors that can specifically recognize these elements in the upstream of ZmERF98.In yeast one hybrid experiment,the bacterial colony of EXORDIUM-pLacZi+ZmERF98-pB42AD in the experimental group didn’t showed blue.In this study,ZmERF98 was found to be a negative regulator of salinity tolerance in maize through transcription regulation network construction,gene function analysis and other results.The mechanism by which the negative salt regulator ZmERF98 needs further research.