Seasonal variation of fungal communities on roots of Allium tricoccum (wild leek) in a mature mixed hardwood forest

Background/Question/Methods

Herbaceous plants are important components of northern hardwood forests, comprise a significant proportion of annual litter fall, and affect nutrient cycling. Many of these plants are colonized by mycorrhizal fungi that act as an extension of their root system and enhance their nutrient uptake. Most herbaceous plants form relationships with arbuscular mycorrhizal fungi (AMF), and may also be associated with non-AMF fungi. We examined the fungal community of the Allium tricoccum Ait. (wild leek) root system for one growing season to assess whether colonization by AMF and other fungi varied seasonally and spatially. Whole plants were collected along a transect at eight time points to coincide with observable phenological stages, including leaf emergence, leaf senescence, flowering, fruiting, seed set, and dormancy. DNA was extracted from root tissue and amplified with primers specific for AMF and with general fungal ITS primers, and analyzed using T-RFLP. Above- and below-ground plant tissues were dried and ground for nutrient (C, N, and P) analysis.

 Results/Conclusions

We found that AMF communities changed significantly over the course of the growing season (MRPP analysis, P = 0.02), with communities from late summer (i.e. during fruit production and seed set of the plants) significantly different from communities during times of spring growth, flowering, and winter dormancy. AMF communities at other times of the year did not vary significantly from one another. We found no changes in AMF communities along our sampling transect, suggesting that season affected AMF communities of A. tricoccum more than spatial variation. General fungal communities on roots also varied seasonally (MRPP analysis, P = 0.02), with communities from spring and early summer significantly different than communities from late summer and autumn. In contrast to AMF communities, spatial location significantly affected general fungal communities on A. tricoccum roots (MRPP analysis, P < 0.01). The changes in AMF and general fungal communities on A. tricoccum roots suggest that these herbaceous plants may rely on different groups of fungi as the plants change phenologically throughout the growing season.