Transcriptomic Analysis of Camellia oleifera in Response to Drought Stress Using High Throughput RNA-seq

Camellia oleifera Abel, a woody oil plant of major economic value, has strong ability for stress resistance. However, insufficient genetic and genomic information hinders the research into the mechanisms of its stress response. In this work, Illumina Genome sequencing platform was used for de novo assembling the transcriptomes of leaves from C. oleifera seedlings grown under optimal (control) and drought conditions. A total of 66570 unigenes with a mean length of 659.78 bp were assembled, amongst which 35259 unigenes could be annotated using the NCBI nr database, Swiss-Prot protein database, Cluster of Orthologous Groups of protein (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In addition, 10869 simple sequence repeats (SSRs) were mined in the leaf transcriptome of C. oleifera. In a comparative transcriptome analysis, when large numbers of differentially expressed unigenes (DEUs) were detected at different stages of drought stress, most unigenes were downregulated under the stress. In the KEGG pathway enrichment analysis, some important KEGG metabolic pathways of C. oleifera were discovered, such as circadian rhythm, flavone and flavonol biosynthesis, and ribosomal structure. Our studies provide a comprehensive map of physiological and molecular responses of C. oleifera to drought stress.