Construction and sequence analysis of a normalized full-length cDNA library of Dendrobium officinale

OBJECTIVE: In order to obtain functional genes, a normalized stems cDNA library was constructed from medicinal plant Dendrobium officinale. METHOD: SMART (switching mechanism at 5' end of RNA transcript) cDNA synthesis combined with DSN (duplex-specific nuclease) normalization was applied to construct the normalized full-length cDNA library of D. officinale. RESULT: The titer of cDNA library was about 1.3 x 10(6) cfu x mL(-1) and the average insertion size was about 1.5 kb with high recombination rate (93.9%). Random selected 163 positive clones were sequenced at single side. Bio-information analysis indicated that 147 from 150 high-quality unique sequences matched corresponding homologous proteins, and they participated in various biological processes based on GO (gene ontology). There were 8 clones with complete coding sequence, which presumed to be full-length genes. CONCLUSION: These results showed preliminarily that we successfully constructed a normalized full-length cDNA library of D. officinale which could be used to screen the functional genes related to metabolic pathways of medicinal ingredients.