Development of microsatellites of Dendrobium officinale and its application in purity identification of germplasm

Simple sequence repeat (SSR) was used to investigate the genetic diversity and structure of  Dendrobium officinale.  A total of 15 primer pairs with stable and repeatable polymorphism were screened out from 60 SSR primer pairs developed by the method of microsatellite enrichment by magnetic beads.  Forty- eight samples of Dendrobium officinale were analyzed in genetic polymorphism.  These loci were polymorphic and displayed 3 to 9 alleles per locus with a mean number of 6.1.  The observed and expected heterozygosities ranged from 0.60 to 0.85 and from 0.49 to 0.85 respectively.  The polymorphic information content (PIC)    of each SSR locus varied from 0.437 to 0.829 with an average of 0.702.  Fifteen primer pairs were used in    Dendrobium cross-species amplification and totally 13 primer pairs were proved to have the transferability in   D. officinale related species.  In addition, 500 tissue culture plantlets of D. officinale were tested for purity  identification by means of PCR amplification with four SSR primer pairs.  The results showed that SSR    technique is a feasible, simple and inexpensive method for determining adulterants in germplasm identification.