Wheat cultivars form distinctive communities of root-associated arbuscular mycorrhiza in a conventional agroecosystem

The effect of plant species on their root-associated arbuscular mycorrhizal (AM) fungi is well studied, but how this effect operates at the cultivar level remains poorly understood. This study investigates how wheat cultivars shape their AM fungal communities. Twenty-one new wheat cultivars were traditionally cultivated in a dryland of northwestern China, and their agronomic traits, soil characteristics and the abundance and community composition of AM fungi were measured. Both spore community in soils and AM fungal phylotypes inside roots were significantly influenced by cultivar even though hyphal abundance, spore density and AM fungal diversity were similar across cultivars. Three out of 16 AM fungal phylotypes interacted with most cultivars, whilst some phylotypes preferred to colonize cultivars with similar agronomic traits. Six wheat cultivars, all which had hosted 6 AM fungal phylotypes, seemed to be generalists. Nestedness analysis and stochastic model fitting revealed that the AM fungal communities colonizing roots were codetermined by deterministic and stochastic processes. A complex pattern of cultivar-AM fungal interactions was observed in this study, and our results highlight that the host effect on the community assembly of AM fungi could be operating on the level of plant cultivar.