Generation and analysis of expressed sequence tags from the tender shoots cDNA library of tea plant (Camellia sinensis)

Tea possesses a great value due to its popularity as a drink and as a source of secondary metabolic products. Up to now, the genomic information and the gene expression patterns of tea plant (Camellia sinensis) have not been studied in detail. In this report, a total of 4320 cDNA clones from a cDNA library of tender shoots from tea plant were randomly sequenced and analyzed. We generated a total of 1684 high-quality EST sequences (average 478 bp in length), among which 1200 ESTs had significant homology with the sequences in NCBI non-redundant protein database by BlastX analysis. The database-matched ESTs were further classified into 12 putative cellular roles based on the functional categories established for Arabidopsis, i.e., metabolism-related category (corresponding 8.3% of total BlastX matched ESTs), energy (26.4%), cell growth and division (3.8%), transcription (3.9%), protein synthesis (17.9%), protein destination and storage (1.7%), transporters (4.7%), cell structure (10.7%), signal transduction (5.4%), disease and defence (9.2%), secondary metabolism (4.8%), and unclear classification (3.4%). One thousand and eight ESTs of known or putative functions could be assigned to 304 functional genes and they were grouped to highly abundant (10%), moderate abundant (30%) and low abundant (60%) expression, respectively. Our study provides an overview of mRNA expression profile and a diverse genetic resource for tea plant research.