Genetic diversity of Dendrobium species revealed by simple sequence repeat (SSR) markers

Dendrobium is an epiphytic orchid, which is highly valued as a cut flowers. The assessment of genetic diversity is crucial to study the relationship between the species and also to develop the novel hybrids. In this study, 25 cross species simple sequence repeat (SSR) markers were screened for amplification in Dendrobium species. Eighteen polymorphic markers were used to estimate the genetic diversity in 15 Dendrobium species. The 18 SSR markers generated a total of 55 polymorphic bands, with an average of 3.05 bands per primer. The observed and expected heterozygosity within the species ranged from 0 to 0.62 and 0.30 to 0.86, respectively. Cluster analysis based on the unweighted pair group method with an average led to a dendrogram with three major groups that coincided for morphological characters mostly for flower colour, flower shape and nature of shoot, but did not coincide with their geographical locations. Results revealed that genetic variation exists amongst the 15 Dendrobium species, which will be helpful in selecting desirable species as a parent for crossing purpose to develop new interspecific hybrids.