Genetic linkage map of EST-SSR and SRAP markers in the endangered Chinese endemic herb Dendrobium (Orchidaceae).

Dendrobium officinale is an endangered orchid from southeast Asia that is known for its medicinal properties in traditional Chinese medicine. We constructed an integrated genetic linkage map of an F(1) population derived from an interspecific cross between D. officinale and D. aduncum (both, 2n = 38), using expressed sequence tag-simple sequence repeats (EST-SSR) and sequence-related amplified polymorphism (SRAP). A total of 349 polymorphic loci, including 261 SRAP loci and 88 EST-SSR loci, were identified for genetic linkage analysis. The software JoinMap 4.0 was used to construct the genetic maps. A total of 157 loci were arranged into 27 major linkage groups, each containing a minimum of four markers, and a further 23 markers were distributed to five triplets and four doublets, the frame map covered a total distance of 1580.4 cM, with a mean of 11.89 cM between adjacent markers. This primary map of the D. officinale and D. aduncum hybrid provides a basis for genetic studies and should facilitate future studies of medical traits mapping and marker-assisted selection in Dendrobium species breeding programs.