Endophytic diversity of hanging velamen roots in the epiphytic orchid Acampe praemorsa.

Background: The ecological functions of the aerial hanging roots (velamen roots) in orchids are not yet fully understood. Aims: The aim of this work was to explore the velamen-root-associated fungal community of Acampe praemorsa and its variation in relation to three different geographic locations and to examine the surface characteristics of the velamen roots in attached positions. Methods: Segments of velamen roots of A. praemorsa collected from different geographic locations of Kerala, India were screened for the presence of velamen-root-associated fungi. The isolated strains were identified by morphological and nrITS DNA barcoding. Surface characteristics of the host-attached or soil-attached velamen roots were analysed using a scanning electron microscope (SEM). Results: The SEM observations of the host-attached or soil-attached surface of velamen roots of A. praemorsa show tufts of unicellular hairs arising from the surface of contact. 211 fungal strains belonging to 15 taxa were discovered from the velamen roots; the nrITS nucleotide sequences of 13 taxa are deposited in GenBank. Conclusions: Fifteen endophytic fungal associates were identified from the velamen roots of A. praemorsa, which showed variation in their community assemblages in plant specimens from different geographic locations. [ABSTRACT FROM AUTHOR]