Abstract
Background and Aims
In coastal grasslands carbon cost of arbuscular mycorrhizal (AM) fungi is a crucial factor for the successful establishment of juvenile plants grown under the canopy of large plants that restricts their photosynthesis. Network competitor (NC) fungi that colonize via hyphal networks may be less costlythan soil-propagule-mediated colonizer (SP) fungibecause C cost for colonization could be covered by the donor plant of the networks.
Methods
Intact root-soil-core samples (NC inocula) and root-zone-soil samples (sieved before inoculation, SP inocula) were collected from a coastal grassland, and seedlings of Miscanthus sinensis were grown with both inocula and either with the NC or SP inocula with or without shading. DNA was extracted from the root, and fungal LSU rDNA was amplified and sequenced to assign to AM fungal operational taxonomic units (OTUs). All AM fungi that occurred with the SP inocula were defined as SP fungi, whereas those that occurred uniquely with the NC inocula were defined as NC fungi.
Results
Shading increased the genus richness of SP fungi, but not that of NC fungi, without changing OTU richness, which was due to the replacement of several Glomerales SP fungi with those that belong to diverse genera in non-Glomerales under the shaded conditions.
Conclusion
These observations suggest that cost of SP fungi is comparable to that of NC fungi and, further, that Glomerales fungi are generally less competitive under which photosynthesis of the host is restricted, providing new insight into the selection of AM fungal partners by plants.