Genetic diversity in some Indian Bulbophyllinae (Orchidaceae) with reference to ecological adaptability and phylogenetic significance
Genetic variability among Bulbophyllum Thou. belonging to the subtribe Bulbophyllinae, tribe Dendrobieae has been studied by using morphological and molecular markers, such as SDS-PAGE protein profiles and RAPD analysis. The orchid flora of India has been deteriorating due to habitat destruction and indiscriminate collection. There is an urgent need to evolve conservation strategies for this specialized ornamental angiosperms. For anatomical studies, microtome sections were prepared whereas for molecular analysis CTAB and PCR techniques were followed. Adaxial epidermal cells in leaf were 2-3 times larger in their size than abaxial ones. Absorbing trichomes were reported from all the investigated taxa. Velamen roots were associated with tilosomes especially in single-layered velamen taxa. The high diversification of vegetative characters is also exemplified by adaptation to various habitats. Plants collected from Darjeeling Himalaya were showing more xeric characters than that of Arunachal Pradesh. However, with respect to velamen, plants collected from Arunachal habitat showed some xeric characters. From the anatomical data, it is evident that not only the geographical conditions and type of habitat but also the nutrient supply of host-tree on which orchid growing, is playing vital role in survivability of epiphytic orchids. The UPGMA dendrogram based on RAPD analysis showed that all taxa of Bulbophyllum section Cirrhopetalum are scattered among all clusters in the dendrogram. This indicates that the characters possessed by the section Cirrhopetallum are shared by other sections of the subtribe Bulbophyllinae. This strengthens the view of Schlecter that other sections of Bulbophyllum must have evolved from the section Cirrhopetallum.
Ramesh, G., Ramudu, J., Khasim, S.M. and Thammasiri, K. 2017. Genetic diversity in some Indian Bulbophyllinae (Orchidaceae) with reference to ecological adaptability and phylogenetic significance. Acta Hort. (ISHS) 1167:187-196
Bulbophyllum, Orchidaceae, anatomical adaptations, SDS-PAGE, RAPD, phylogeny