Drivers of the taxonomic and functional diversity, and functional composition of fungal endophyte communities in crucifers

Ecological traits that filter the occurrence of species and functional groups responding to environmental and other variables are keys to the assembly processes of communities, but little is currently known about these processes for endophytic fungi. A trophic-based joint species distribution model was applied to endophyte occurrence by 110 crucifer-inhabiting fungal species isolated from Brassica rapa, Raphanus sativus and Brassica (Aroma, from 21 sites with different landscape compositions and pesticide use over four seasons. We investigated the responses of taxonomic diversity, function diversity and functional composition. Season, plant identity and plant part were significant factors in shaping all indices. Elevation and grassland shaped taxonomic diversity and functional composition but not functional diversity. RLQ and fourth corner analysis showed that pathotroph, symbiotroph, dung saprotroph, endophyte, epiphyte and plant pathogen were positively correlated with autumn and summer seasons, white cabbage, leaf tissues and elevation; while saprotroph, animal pathogen, fungal parasite, undefined saprotroph, wood saprotroph and yeast-like were positively correlated with spring and winter seasons, root tissues, grassland and water in the landscape. Our results show that taxonomic diversity, functional diversity and functional composition are partially coupled, indicating that variable filters could influence cruciferous fungal endophytes at species and trait levels.