Mycorrhizal status of Phlebopus bruchii (Boletaceae): does it form ectomycorrhizas with Fagara coco (Rutaceae)?

摘要

Fagara coco (Gill.) Engl, is a native tree found in the mountains of Central Argentina. It generally grows together with the edible bolete Phlebopus bruchii (Speg.) Heineman & Rammeloo. This association is considered to be an ectomycorrhizal symbiosis. To test the hypothesis of their co-occurrence as mutualistic partners, we studied the mycorrhizal colonization in roots from either natural stands or inoculated with spores of P. bruchii in both, the greenhouse and in pure culture experiments. However, no ectomycorrhizal (ECM) colonization was detected. Instead, roots collected from the field were colonized by arbuscular mycorrhizal (AM) fungi, showing a dual infection of Arum- and Paris-type morphologies. The percentage of AM mycorrhizal colonization varied according to the season, with the highest occurring in the autumn. Spores of ten Glomalean taxa were isolated from the F. coco rhizosphere. Based on our results and previous data, we suggest that the behavior of the genus Phlebopus is an exception to the mycorrhizal habit found in most Boletales.