Biogeographic Patterns of Ectomycorrhizal Fungal Communities Associated With Castanopsis sieboldii Across the Japanese Archipelago

Abstract

Biogeographic patterns in ectomycorrhizal (ECM) fungal communities and their drivers have been elucidated, including effects of host tree species and abiotic (climatic and edaphic) conditions. At these geographic scales, genotypic diversity and composition of single host tree species change with spatial and environmental gradients, reflecting their historical dispersal events. However, whether the host genotypes can be associated with the biogeographic patterns of ECM communities remains unclear. We investigated the biogeographic pattern of ECM fungal community associated with the single host species Castanopsis sieboldii (Fagaceae), whose genotypic diversity and composition across the Japanese archipelago has already been evaluated. ECM communities were investigated in 12 mature Castanopsis-dominated forests covering almost the entire distribution range of C. sieboldii, and we quantified the effect of host genotypes on the biogeographic pattern of ECM fungal communities. Richness and community composition of ECM fungi changed with latitude and longitude; these biogeographic changes of ECM community were significantly correlated with host genotypic variables. Quantitative analyses showed a higher relative explanatory power of climatic and spatial variables than that of host genotypic variables for the biogeographic patterns in the ECM community. Our results suggest historical events of host dispersal can affect the biogeographic patterns of the ECM fungal community, while their explanation power was lower than that for climatic filtering and/or fungal dispersal.

The ectomycorrhizal fungal communities react differently to climatic, edaphic and spatial variables depending on their host species

“…The full dataset of the runs for F. crenata forests was deposited in the DRA (accession #DRA004595). The obtained reads were processed following the procedure described by Matsuoka et al, (2019). After trimming (Kunin et al, 2010) and demultiplexing, 382,207 reads remained.…”

“…After trimming (Kunin et al, 2010) and demultiplexing, 382,207 reads remained. Then, 315,685 reads from 234 C. sieboldii samples (trimmed and demultiplexed reads from Matsuoka et al, 2019) were added, resulting in a total of 697,892 reads for further analyses. These 697,892 reads were assembled, and then singletons, potentially chimeric sequences, and pyrosequencing errors were removed.…”

“…For ECM fungal communities associated with C. sieboldii, raw sequence data were obtained from Matsuoka et al, (2019) The mean annual temperature (MAT) and mean annual cumulative precipitation (MAP) ranged from 12.9℃ (at site C1) to 21.8℃ (C12) and from 1838.9 (C1) to 3754.0 (C10) mm, respectively (Table 1), according to the records of the Japan Meteorological Agency. The 12 sampling sites cover almost the entire distribution range of C. sieboldii (see details in Matsuoka et al, 2019).…”

“…The permission for root sampling was obtained from the Ehime Forest Management Station and the Hakusan Nature Conservation Office. Sampling methods and experimental procedures were the same as those used by Matsuoka et al, (2019).…”

“…For edaphic data, we measured three variables for each soil block: soil water content, pH and C:N ratio, following the method used by Matsuoka et al, (2019). Edaphic data for C. sieboldii samples were obtained from Matsuoka et al, (2019).…”