ISHS Acta Horticulturae 616: I International Symposium on Acclimatization and Establishment of Micropropagated Plants
ANATOMICAL STUDY ON THE DEVELOPMENT OF IN VITRO ORCHID ROOTS INFECTED WITH MYCORRHIZA |
| Authors: | H.K-L. Goh, W-Y. Ng, S-Y. Huang, I. Tan, X-S. Zhang, F-Y. Than, C-L. Lim-Ho |
| Keywords: | Biological microtechnique, co-culture, orchid mycorrhiza, tropical orchids, Vanda ‘Tan Chay Yan’ |
| Abstract:
Tissue culture techniques are now widely used to produce commercially grown orchids. This process takes about 8-12 months to produce plantlets large enough to withstand the rigours of nursery conditions. However, during the acclimatization phase, tissue-cultured plantlets undergo a lag phase before they are able to establish. In nature, orchid plants rely on their close association with mycorrhiza fungi for growth and development. Thus, we have developed a method to infect in vitro orchid roots with mycorrhiza. Stage III micropropagated orchid plantlets were artificially inoculated with mycorrhiza strain MS6A (isolated from Mokara Sunkist) in vitro. The roots of the plantlets were harvested 5, 8 and 20 weeks after inoculation to study the stages and development of mycorrhiza infection. Using biological microtechniques, the orchid roots were cut into sections of 8 m thickness and stained with 1% Toludine Blue O. The slides were examined under light microscope and the developmental stages of mycorrhiza in the cells were examined. The aim is to study the developmental stages of the association of mycorrhiza strain MS6A in Vanda ‘Tan Chay Yan’ orchid plantlets in vitro. Orchid roots after 5 weeks of infection had masses of fungal hyphae at the velamen region. At week 8, intracellular fungal aggregates have spread to the cortical cells. At week 20, coils of fungal hyphae, also known as pelotons, have infected cells near the central vascular cylinder. This was similar to the infection pattern observed in plants in vivo. | |
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