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Differential effects of mycobionts with different ecological strategies
on oak morphology
talk
session 7
HERRMANN1, SYLVIE, FRANÇOIS
BUSCOT1 & JEAN CHARLES MUNCH2
1Soil Biology, Federal Center for Agriculture
Research, Bundesallee 50, D-38116 Braunschweig, Germany
2Soil Ecology, GSF-Research Center for Environment
& Health, Postfach 11 29, D-85758 Oberschleissheim, Germany
ICOM1 Abstract
The presented work is a unique approach on influence of mycobionts
with different ecological strategies on morphology of the aerial and
subterranean parts of plants. Micropropagated oaks were
mycorrhized in a semi sterile system in which roots grow two
dimensionally in a sterile recipient. Non destructive morphological
observations were performed with a digitized image analysis system
during the culture and completed by destructive analyses at the end
of the assays. The morphological effects differed extremely
according to the mycobiont species. Certain fungi influenced plant
development only quantitatively whereas others modified internal
correlations concerning leave formation and production of the
different root categories (main roots, mother roots of 1st and 2nd
orders, fine rootlets). With certain mycobionts, the morphological
effects started before mycorrhization. For example, Piloderma
croceum stimulated both leave and root production before a
symbiotic relationship was detectable. This stimulating effect was not
reflected by weight increase, suggesting that the fungus links
photoassimilates before it forms mycorrhizae. The experimental
models we established allow exciting comparative studies on
recognition prior to formation of ectomycorrhizas. They are also
useful to interpret influence of mycorrhization on dynamics in
individual plants and in plant communities.