Construction and Analysis of cDNA Expression Library from the Leaves of Dendrobium candidum Wall. ex Lindl / 广州中医药大学学报

ABSTRACT

[Objective] cDNA expression libraries from the leaves of Dendrobium candidum Wall. ex lindl. were constructed to supply evidence for the clones of the full-length genes involved in the biosynthesis of bioactive compounds. [Methods] Total RNA was isolated and purified from tender leaves of 4-year-growing Dendrobium candidum by using Trizol single-step method. cDNA was synthesized by long distance polymerase chain reaction (LD-PCR) and then was connected to ?TripIEX2. After that, the recombinant bacteriophages were packaged and cDNA library of Dendrobium candidum was constructed. The titer of cDNA library was expressed as the number of phage formation unit (pfu) per milliliter and the inserted fragment was identified by PCR amphfication. [Results] cDNA expression libraries from the leaves of Dendrobium candidum were constructed successfully. The titer of the original library was 4.3?105 pfu/mL and 3.1?105 clones in total, with a recombinant rate of 97.6%. The amplified titer was 6.8?109pfu/mL. PCR amplification suggested that the inserted cDNA fragments ranged from 0.5 to 2.0 kb, mostly from 1.2 to 1.7 kb. [Conclusion] The constructed Dendrobium candidum cDNA library has a higher titer, a higher recombinant percentage and larger inserted fragments.