| Autor: |
Zelmer, Carla D., Cuthbertson, Lisa, Currah, Randy S. |
| Zdroj: |
Mycoscience; December 1996, Vol. 37 Issue: 4 p439-448, 10p |
| Abstrakt: |
The identity and ecological role of fungi in the mycorrhizal roots of 25 species of mature terrestrial orchids and in 17 species of field incubated orchid seedlings were examined.Isolates of symbiotic fungi from mature orchid mycorrhizas were basidiomycetes primarily in the genera Ceratorhiza, Epulorhizaand Moniliopsis;a few unidentified taxa with clamped hyphae were also recovered. More than one taxon of peloton-forming fungus was often observed in the cleared and stained mycorrhizas. Although Ceratorhizaand Epulorhizastrains were isolated from the developing protocorms, pelotons of clamped hyphae were often present in the cleared protocorms of several orchid species. These basidiomycetes are difficult to isolate and may be symbionts of ectotrophic plants. The higher proportion of endophytes bearing clamp connections in developing seeds than in the mycorrhizas is attributed to differences in the nutritional requirements of the fully mycotrophic protocorms and partially autotrophic plants. Most isolates of Ceratorhizadiffered enzymatically from Epulorhizain producing polyphenol oxidases. Dual cultures with thirteen orchid isolatesand five non-orchid hosts showed that some taxa can form harmless associations with non-orchid hosts. It is suggested that most terrestrial orchid mycorrhizas are relatively non-specific and that the mycobionts can be saprophytes, parasites or mycorrhizal associates of other plants. |
| Databáze: |
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