Characterization and taxonomic placement of Rhizoctonia--like endophytes from orchid roots

Abstract

Twenty-one Rhizoctoniu-like fungal strains were isolated from the roots of four terrestrial orchid species from various locations in Hong Kong. The cultural morpholon, uclear number of the hyphal cell, pore ultrastructure, and RAPD and CAPS analyses of rDNA fragments revealed that nlost of these isolates Tvere associated with the genera Clatorlziza and Epulorhizn. W Dan alysis showed the presence of genetic diversity between the isolates froin different hosts and locations. The compatibility between a selection of these Ceratorhiza and Epulorhiza isolates and 14 orchld species was determined using a symbiotic gerrninatlon method The germinatioil and development of three orchld species, .Arundina chinensis, Spathoglottis poubescens, and Spiranthes honkongensis, were strongly stimulated by the Epulorhiza isolates. Habenaria dentata was found to form symbionts successfully with a Ceratorhiza isolate.