| In addition to the largest grain crop in China,Maize(corn,Zea mays L.)is also known as an important feed,fruits and vegetables,and energy crop,and plays an important role in the development of national economy.Abiotic stresses are the main limiting factors affecting maize yield.The occurrence of abiotic stresses,such as salinity,drought,low temperature and high temperature,have serious impacts on the growth and development of maize.Seedling stage is the most sensitive period of maize when affected by abiotic stresses.Thus,it is of great significance to identify the differentially expressed genes(DEGs)responding to abiotic stresses,to elucidate the molecular biological mechanism of these genes,and to dig the excellent allelic variation for molecular design breeding of maize resistance to stresses.In this study,high salinity,drought,high temperature and low temperature stress treatments were carried out on maize inbred line B73 at the seedling stage(three-leaf stage).Based on high-throughput transcriptome sequencing(RNA-Seq),the transcripts under these stress conditions were detected.The DEGs responding to each stress conditions were further detected.In addition,the regulatory pathways of these DEGs were further annotated using some bioinformatics methods.The main results of this thesis are shown in following:(1)a total of 1661,2019,2346 and 1481 DEGs were detected for high salinity,drought,high temperature and low temperature stresses,respectively;(2)all these 5330 genes are significantly enriched in 51 GO terms,and 4 GO terms contain more than 500 DEGs,including metabolic proces,catalytic activity,biological regulation and transferase activity;(3)these DEGs are mainly associated with plant hormone metabolism,signal transduction,the biosynthetic pathways of transcription factor(TFs),very long chain fatty acids(VLCFAs),and lipids,according to the functional annotation of them;(4)a total of 167 DEGs detected in all of these four stress conditions,including 10 up-regulated transcription factors(5 ERFs,2 NACs,1 ARF,1 MYB,1 HD-ZIP)and 2 down-regulated transcription factors(1 b-ZIP,1 MYB),suggesting that maize may have the same response mechanism to different abiotic stresses.These results also illustrated that there are both similar and different response mechanisms to these abiotic stresses differentially expressed genes were consistantly expressed under different stress conditions for maize leaves in seedling stage.In this thesis,DEGs under high salinity,drought,high temperature and low temperature conditions were identified based on transcriptome analysis,and the metabolic pathways and regulatory pathways involving of them were elucidated.These results will provide important references for identifying and functional detecting of abiotic stresses responding genes.In addition,these results is also importing in digging allelic variations and molecular design breeding in improving the abiotic stress resistance of maize. |
