Transcriptome Analysis Of The Drought Stress Response Of Artemisia Sphaerocephala

Artemisia sphaerocephala is one of the dominant species in drifting, semi-drifting and semi-fixed sand land in arid desert region in northwest China, which is important to windbreak and sand fixation. In this paper, I'm used the Illumina HiSeq2500 sequencing platforms to sequence transcriptome of A. sphaerocephala in three levels:normal growth, moderate drought stress, under severe drought stress, in each of them with three repeat experiments, obtaining a great deal of information of A.sphaerocephala responsing arid gene expression, and then analyzed the information, selected and identified SSR site. The main results are as follows:1. A total of 43.41Gb clean data were get, all kinds of Q30 base percentage were not less than 91.33% by sequencing using Illumina HiSeq2500 sequencing platform. The pair-end reads average values of the clean data of control group, moderate stress group, severe stress group were as follows:20,560,731,18,847,793,18,031,158, and the total base number respectively:5,179,877,049,4,818,908,086,4,541,562,901.2. After the de novo assembly, it got contig 18,016,537, transcript 307, 395, unigene 128,460, and 44,258 (34.45%) unigenes among them are annotated to NR, Swiss prot, Pfam, KOG, GO and COG database. In which, a total of 21,787 unigenes were annotated to 41 GO terms,12,107 unigenes were subjected to 24 clusters of COG families, and 8,811 unigenes were mapped to 117 metabolic pathways in the KEGG.3. Differentially expression genes analysis by DESeq showed that:The differentially expressed genes of the control and the moderate stress, the control and severe stress, moderate stress and severe stress were respectively: 445,1582 and 68, and with 128,645 and 27 up-regulated genes,317,937 and 41 down-regulated genes respectively.4. To moderate stress compared with the control group, a total of 224 differentially expression genes were annotated to the GO database. The most enriched items were mainly related to drought stress, in the "Biological Process", the "Oxidation-reduction Process", "Metabolic Process", "Response to Stress", "Phosphorylation", "Carbohydrate Metabolic Process" were enriched the best, which are closely related to plant stress resistance; In the "Cellular Component", the most enriched items were the "Plasma Membrane", " Membrane ", " Integral Component of Membrane "and so on, indicated the characters of cell membrane changed under drought stress; In the "Molecular Function", the most enriched items which related to drought stress were "ATP Binding", "Metal Mon Binding ", "Protein Kinase Activity".The severe stress compared with the control group, the differential expression genes were more, and a total of 769 were annotated to GO database. Enrichment items were similar to which under moderate stress conditions, but differentially expressed genes under the same item were more. The "Chloroplast Stroma" was enriched more in the "Cellular Component" under the severe stress, which is different from the situation under the moderate stress, because of the photosynthesis of the A. sphaerocephala was influenced. This phenomenon was more prominent in the genes differentially expressing in severe and moderate stress, although only 37 differential expression genes were annotated to the GO database, but main related to light response.In the KEGG pathway, the higher significant enrichment were" Photosynthesis-antenna Proteins", "Phenylpropanoid Biosynthesis", "Phenylalanine Metabolism", "Plant-pathogen Interaction" and so on.5. The function of differentially expression genes were predicted using the seven database,118 unigenes was predicted to be associated with functional genes; 71 was predicted to be transcriptome factor, in which 32 up-regulated,39 down-regulated.6. About 5,692 SSR loci was identify in the total length of 37,909, 316bp of sphaerocephala assembled data, spread over 4,625 sequence, the frequency appears SSR 4.43%,the average produced a site every 6.66 kb. A lot of 15 pairs of primers after strict screening were tested, and they were as expected as well with certainly polymorphism.