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Distribution and characterization of endophytic fungi from tropical orchids
Author
Noorfaezah Sadon
Supervisor
Tham, Foong Yee
Abstract
Orchids are known to form symbiotic mycorrhizal associations with fungi in nature. In the current study, a survey of the distribution of mycorrhizal associations in 61 species of tropical orchids, mainly from Malaysia and Indonesia, was canied out. Of the orchids sampled, 77% showed the presence of pelotons or fungal hyphal coils in the cortical cells of the roots. The extent of the mycorrhization within the roots ranged from 5% to 80% but generally, tropical orchids sampled had sporadic mycorrhization of less than 20%. A total of 33 fungal endophytes were recovered from the roots of 21 orchid species cultured via thin root sections plated on 1.5% Tap Water Agar. Based on morphological characterization, the isolates established included the Rhizoctonia-like fungi generally known to be associated with orchids as well as a number of Colletofrichum sp. and Fusariurn sp. The latter non-basidiomycetous fungi are often discounted as orchid mycorrhiza because their biological roles have as yet not been widely demonstrated. However, their common occurrence in the present study suggests that they may be important in nature and could have a role in nutrient gathering and sequestering and their presence may influence the competitive ability of the orchid hosts. Molecular characterization using the internal transcribed spacer (ITS) region of genes coding for the ribosomal RNA (rRNA) of the fungal isolates was also used to generate additional characters to supplement data based on morphological features to further determine the relationship of the fungal associates.
Date Issued
2005
Call Number
QK495.O64 Noo
Date Submitted
2005