Systemic Analysis Of RNA-seq Expression Patterns In Mazie Under Drought And Phylogenetic Analysis Of The WRKY Transcription Factor

Drought and other abiotic stress is the serious environmental stresses affecting plant growth,development,crop yield,and productivity.To cope with environment stress,plants have evolved complex adaptive mechanisms,including regulation of transcription,epigenetic plasticity,metabolic reprogramming,and so on.Transcription factors play a central role in the transcription networks though regulating the expression of hundreds of downstream genes.Here,drought-sensitive maize B73 was used as the material,and the data of 24 groups of transcriptions(ear,tassel,leaf in V12,V14,V18,R1 under normal and drought stress)were analyzed.The co-expression network was constructed and the drought-responsive mechanism of maize was studied.In addition,the evolution and drought response of WRKY transcription factors in maize were further analyzed.The results are as follows:1.By alignment,assembling,and estimation of gene expression level of the RNA-seq data,27885 genes were expressed at least one set of samples,while the 52.24%(14625/27885)was expressed in all 24 samples.Further differently expressed genes(DEGs)analysis revealed 11284 DEGs.The number of DEGs was the highest in the R1 period of ear and leaf under drought stress,while the number of DEGs in tassel was relatively small.2.We obtained 10 modules by using the WGCNA package.The different modules were related to the specific expression of tissue and development stages,suggesting different functions.Further GO enrichment analysis revealed that these functions included chloroplast photosynthesis,enzyme activity,pollen tube growth,membrane transport,cell wall,stress response,transcriptional regulation,hydrolase activity,and so on.The co-expression network contained 844 hub genes,and 15.4% of the hub genes underwent genome-wide replication events.These genes in same modules have a higher correlation coefficient,indicating that their function tends to be conserved.3.Combining a regulatory networks,we focus on transcription factors that play a pivotal role in co-expression networks.It was found that bHLH,NAC,C2H2 and other transcription factors family play a dual role in responsing to drought stress and development.4.WRKY transcription factor is a plant-specific transcription factor that plays an important role in biotic or abiotic stresses.We selected the WRKY transcription factor for evolutionary analysis.It was identified that the maize genome contained 120 WRKY gene family members.Gene structure and motif compositions analysis showed that differentWRKY subfamilies had their own unique characteristics.The expression profiling of ZmWRKY genes based on the global microarray data revealed eight genes responded to drought stress.RNA-Seq profiling showed that 58 ZmWRKY genes were induced in drought stress.Seven genes were used to identify drought stress by real-time quantitative PCR.Further the cis-elements analysis of ten candidate ZmWRKY genes showed that the putative promoter of each gene includes at least a drought-responsive element.The protein-protein interaction analyses indicates that there may exist interactions between 21 differentially expressed WRKY transcription factors.