Analysis Of Transcriptome And Histone Methylation Modification Levels In Maize Leaf Under Drought Stress

Maize(Zea mays L.)is an important crop,feed and industrial raw material in the world.Drought stress seriously threatens maize production.It is efficient that digging new drought resistance genes and breeding new drought-resistant maize varieties,which can reducing the harm of drought stress.The rise of high-throughput sequencing technology provides a new technology for large-scale excavation of drought-resistant genes.In this study,we used maize inbred line Chang 7-2 as material,then drought stress treatment was carried out on 3-leaf maize.Using RNA-seq and ChIP-seq techniques,the transcription and histone modification levels of maize leaves responding to drought stress were analyzed at genome level,differentially expressed genes were identified,and functional annotations were made.Finally,some key candidate genes related to drought resistance in maize were screened.The main results are as follows:(1)In RNA-seq data,compared with the control,1882 differentially expressed genes were found in 3-day-drought maize leaves,including 1258 up-regulated genes and 511 down-regulated genes;1054 differentially expressed genes were found in 6-day-drought maize leaves,of which 544 were up-regulated genes and 510 were down-regulated genes.Functional annotation of these differentially expressed genes revealed that the differentially expressed genes were mainly related to nucleic acid binding transcription factor activity,calcium binding,protein kinase activity,chlorophyll binding,hormone response,oxidoreductase activity and catabolism of hydrogen peroxide.(2)In ChIP-seq data,the H3K4me3 levels of 2277 genes changed in 3 days of drought treatment compared with control,and the H3K4me3 levels of 1868 genes changed in 6 days of drought treatment.Functional annotation of these differentially expressed genes revealed that they were mainly involved in cell composition,nucleic acid template transcription,regulation of cell metabolism,transmembrane transport,active regulation of stimulus response,transmembrane transport of inorganic ions,and auxin response.(3)The correlation analysis of RNA-seq and CHIP-seq data of maize leaves showed that 115 and 59 genes changed not only at the transcriptome level,but also at the histone modification level on the 3rd and 6th days of drought treatment.Functional annotation of these genes revealed that they were mainly involved in cell composition,nucleic acid template transcription,regulation of cell metabolism,transmembrane transport,active regulation of stimulus response,kinase activity,inorganic ion transmembrane transport and auxin response.This study analyzed the differentially expressed genes under different degrees of drought stress.These differentially expressed genes are involved in stress signal perception,calcium signal transduction,ABA signaling pathway and so on,which provides data basis for further identification and functional analysis of drought-related genes.