[Transcriptome analysis for leaves of five chemical types in Cinnamomum camphora]

Camphor tree (Cinnamomum camphora) is a representative species in Lauraceae family, and can be subdivided into five types: linalool, camphor, cineol, iso-nerolidol and borneol. In this paper, the leaves transcriptomes of Cinnamomum camphora were sequenced with the platform of Illumina HiSeq™ 2000. Based on the GO (Gene Ontology), COG (Clusters of Orthologous Groups), and KEGG (Kyoto Encyclopedia of Genes and Genomes) database, the function classification, pathway annotation, and the coding sequence prediction of all-Unigenes were carried out. 156 278 Unigenes with an average length of 584 bp and N50 (N50 value is defined as the Unigene length where half the assembly is represented by Unigenes of this size or longer) of 1 023 bp were generated by de novo assembly. A total of 5 5955 Unigenes (35.80%) were annotated through similarity comparison, in which 24 717 and 21 806 Unigenes were assigned into GO and COG, respectively. By searching KEGG database, 3 350 Unigenes were involved in biosynthesis of secondary metabolites, in which 424 Unigenes were involved in monoterpenoids, diterpenoids, sesquiterpenoids, and terpenoid backbone biosynthesis. The analysis of monoterpenoids biosynthesis pathway showed that 9 Unigenes likely encode (+)-linalool synthase, and their expression levels were higher in linalool type but lower in cineole type. This study provides a foundation for further characterizing the functional genes in C. camphora.