Research On Low Temperature Response Gene Expression Profiles Of Ammopiptanthus Mongolicus Basing On MRNA Transcriptome And Small RNA Transcriptome

Ammopiptanthus mongolicus is the only super-xerophytic and broad-leaved evergreen shrub in desert area of China. Kinds of resistance genes from A. mongolicus have large values of exploitation and utilization for the comprenhensive resistance characteristic of drought, high temperature, cold temperature, corrosion and alkali. In this dissertation, Illumina high-throughput sequencing technology was carried out to analyze the regulation rule of differentially expressed proteins in cold-strssed A. mongolicus by mRNA transcriptome and small RNA transcriptome. Basing on the large amount of mRNA and small RNA sequence data, the transcriptome database of A. mongolicus leaves in normal temperature, digital expression profile of cold stress responsive genes, and small RNA differential expression profiles between normal temperature and cold stress were first established. The mian conclusions were as follows:(1) In the digital transcriptome database of A. mongolicus leaves in normal temperature, there are27,480,454reads, which contain2,325,124,260nucleotide sequences.103,838Contigs were obtained and matched out59,141Unigenes,25,551of which have similarities with COG database genes. The KEGG annotation result of Unigenes showed that4,650Unigenes accounting for21.26%are related to biochemical metabolic pathway,2,138Unigenes accounting for9.77%are related to of secondary metabolic biosynthesis,1,300Unigenes accounting for5.94%are related to plant hormone transduction, only one Unigene is related to glycolipid synthesis.(2) Comparison of normal temperature and cold stress transcriptome database of A. mongolicus leaves, there are56,144differentially expressed Unigenes in cold stress A. mongolicus leaves. GO annotation result of expression profile showed that36,775Unigenes can be functionally annotated; KEGG Pathway annotation result of expression profile showed that there are21,875Unigenes can be functionally annotated,8,436of which are significantly differentially expressed genes. The results revealed that lots of trait regulatory genes involving many metabolic pathways are significantly differentially expressed in cold-stressed A. mongolicus leaves.(3) In small RNA expression profiles of normal temperature and cold-stressed A. mongolicus, there are3,123,135small RNA species, which contain a total of13,204,830sequences. In cold-stressed sample, there are1,387,310small RNA species, which contain1,683,273sequences. In normal temperature sample, there are1,318,600small RNA species, which contain1,611,753sequences. Genbank and Rfam annotation results showd that83,199small RNA species (3,201,179sequences) in cold-stressed small RNA transcriptome are functionally annotated, where94,474small RNA species (3,326,928sequences) in normal temperature small RNA transcriptome are functionally annotated. Moreover, the functionally unannotated small RNAs account for51.74%and49.38%of cold-stressed and normal temperature small RNA transcriptome, respectively. The results suggested that a complicated responsive mechanism by differential small RNA transcriptome exists in cold-stressed A. mongolicus.(4) Candidate miRNA precursors of functionally unannotated A. mongolicus small RNAs were analyzed by Mireap (miRNA prediction software from BGI-Shenzhen). There are25new miRNA stem loop structures in cold-stressed A. mongolicus small RNA transcriptome, while18new miRNA stem loop structures in normal temperature small RNA transcriptome. Moreover, base bias and target genes site of these new miRNAs were further analyzed. The results will provide basis for revealling cold-stressed regulatory mechanism of A. mongolicus by small RNA transcriptome.