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Seasonal change in the composition of the mycorrhiza of mayapple, Podophyllum peltatum.
Ingram, Ella*,1, Watson, Maxine1, 1 Indiana University, Bloomington, IN
ABSTRACT- Mutualisms can vary seasonally in the intensity of interactions among participants or in the benefit participants derive from the association. For arbuscular mycorrhizas, the relative presence or absence of mycorrhizal structures such as arbuscules and vesicles can indicate seasonal changes in the nature of the mutualistic interaction. To understand how mycorrhizal function changes through time, we examined seasonal variation in hyphal colonization and in arbuscule and vesicle presence (also measured as % root length colonized (%RLC)) within the roots of the clonal perennial mayapple, Podophyllum peltatum. Hyphal colonization and arbuscule presence peaked in spring and fall, while vesicles were relatively abundant only in fall. Arbuscule presence (and in fall, vesicle presence too) peaked first, followed one month later by a peak in hyphal colonization. The levels of hyphal peaks were roughly equivalent in spring and fall, as were the levels of arbuscular peaks. During peak times, arbuscules accounted for at least 40% RLC. Vesicles always were present at low frequency, peaking at <10% RLC. We conclude that spring and fall are particularly active times of resource exchange in the mayapple mycorrhiza, with these active periods of exchange followed by rapid hyphal growth. In contrast, resource storage within the mayapple mycorrhiza occurs more in the fall than during other times in the year. Our results suggest that examination of hyphal colonization alone, or total root colonization alone, may obscure important aspects of the functional dynamics of mycorrhizal associations.
Key words: temporal variation, mycorrhizas, arbuscular colonization