Girlanda, Perotto, and co-authors used both culture dependent and independent molecular approaches to identify the mycorrhizal fungi associated with each of four orchid speciesOphrys fuciflora, Anacamptis laxiflora, Orchis purpurea, and Serapias vomeraceafound in northern Italy.
The authors isolated fungi from the roots of up to 14 plants of each orchid species and grew them on agar plates for identification. This culture-dependent, in-vitro isolation technique revealed a diverse spectrum of endophytic fungi associated with each orchid species, including mycelia of a group of fungi, Rhizoctonia, that are typically found in these types of orchids.
In an approach that turned out to complement the culture-dependent approach, because it revealed a different suite of Rhizoctonia and basidiomycetous and ascomycetous fungal endophytes, the authors also directly amplified genomic DNA from orchid roots using universal and tulasnelloid-specific fungal primers.
Interestingly, two of the orchid species, Orchis purpurea and Ophrys fuciflora, had lower fungal diversity and more specific mycobiont communities compared with the other two orchids, Anacamptis laxiflora and Serapias vomeracea. Furthermore, when the authors compared the suite of Rhizoctonia fungi found in Serapias vomeracea across different meadows, they found that individual plants did not locally adapt to the fungi present at that location but instead associated specifically with fungi present in similar habitats throughout their range. Girlanda and colleagues conclude that this indicates that, despite being photosynthetic, these orchids do form specific mycorrhizal associations.
"Our paper shows that mycorrhizal specificity is not restricted to fully or partially nonphotosynthetic orchids," notes Girlanda, "because some photosynthetic species ca
|Contact: Richard Hund|
American Journal of Botany