| In this dissertation, Populus simonii Carr. was used as a material for high temperature (42℃,6h) and low temperature (4℃,6h), which is one of key forest resources with lots of good characteristics, such as high tolerance with drought and extreme temperature, and detected differentially expressed genes by poplar genome array. Here, we identified1085cold responsive genes which the expression ratio was greater than4. GO analysis indicated that cold induced genes were enriched in, response to temperature stimulus, response to reactive oxygen species and response to hormone stimulus for biological process. Conversely, GO terms including cellular nitrogen compound metabolic process, photosynthesis and generation of precursor metabolites and energy were enrichment in cold repressed genes. The functional annotation of differently expressed genes revealed these genes involved in photosynthesis, calcium/calmodulin-mediated signal transduction, ABA homeostasis and transport and antioxidant defense systems. Gene expression analysis showed majority of genes involved in photosynthesis were repressed but THF1gene was induced suggesting play important role in the production of vesicles for leaf development under lower temperature conditions. A series of genes involved in calcium/calmodulin-mediated signal transduction, ABA homeostasis and transport and antioxidant defense systems were significantly induced under chilling stress suggesting might play a positive regulator in enhanced low temperature tolerance of poplar. Several transcription factor were detected have divergent expression patterns among different members suggesting these transcription factor have variable function response to abiotic stress. In total,1805genes showed a fourfold or greater expression difference between the high temperature group and control group. Based on gene ontology (GO) classification, the increased genes were classified into9significantly enriched GO terms involved in58pathways, and the decreased genes were classified into39significantly enriched GO terms representing88pathways. Analysis of differently expressed genes revealed these genes involved in photosynthesis, signal transduction, antioxidant defense systems. Of which, we identified165transcription factor (TF) genes differentially expressed under high temperature treatments, and different TF members have different roles in responding to heat stress. Meanwhile, approximately80.6%protection genes have been identified, such as HSPs, aquaporins (AQPs), OPEN STOMATA1(OST1)/SRK2E, and they were involved in various biological processes. Analysing PsMBF1and PsDREB7gene sequences of36individuals in Populus simonii, we found that the frequency of SNP diversity was high in the two genes and LD declined within candidate genes. To our best knowledge, this is the first widespread to identify hundreds of potentially important transcriptome changes responding to abiotic stress in P. simonii, and the results of this study and will be valuable for further study of the molecular mechanisms of abiotic stress tolerance in woody plants. |
