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

[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.

Construction of Subtractive cDNA Library from the Leaves of Dendrobium candidum Wall, ex Lindl. by Suppression Subtractive Hybridization Technology / 广州中医药大学学报

[Objective] Subtractive cDNA libraries from the leaves of D. candidum were constructed to supply evidence for the clone of dendrobine-biosynthesis-associated genes. [ Methods ] Suppression subtractive hybridization ( SSH) technology was used. With the cDNA of perennial leaf as the tester and that of annual leaf as the driver, forward and reverse hybridization was performed. The two obtained subtracted cDNA fragments were cloned into PointTMXa-1 plasmid vectors, and then the vectors were transformed into E. Coli JM109. The inserted fragments were amplified by PCR and then identified. [Results] The subtractive cDNA libraries related with dendrobine-biosynthesis-associated genes were successfully constructed. The forward and reverse subtractive libraries included 560 and 220 clones respectively. Detected by PCR, the length of the inserted fragments was 550 bp on average. [Conclusion] The constructed subtractive libraries are suitable for further study on the functional genes associated with dendrobine biosynthesis of D. candidum.