Selection of fungi by candidate cover crops

• Potential cover crop species enrich for different fungal community assemblages.
• Different proportions of fungal lineages are recovered by each host species.
• Greatest fungal richness observed in association with wheat and vetch roots.
• Greater recovery of arbuscular mycorrhizal communities observed for legume hosts.

Diversified cropping systems that incorporate year-round ground cover, are known to maintain healthy soils. Information is available for producers regarding the benefits of specific cover crop species for soil fertility, weed and pest management. Even though it is widely recognized that cover crops promote microbial biomass and activity, the specific responses of particular microbial groups to specific cover crop treatments are yet to be understood. In this work we determined differences in diversity and relative abundance of root endophytic fungi recovered by four potential cover crop species grown in a microbe-rich soil inoculum. For this, a trap culture approach was used, were plants of four species were grown in the greenhouse until maturity in a soil mix originating from a prairie remnant. Root endophytic fungi were surveyed through amplicon sequencing of total root DNA, targeting universal fungal and arbuscular mycorrhizae (AM) – specific ribosomal markers. Each host species studied enriched for different fungal community assemblages, with particular fungal lineages being differentially abundant across hosts. In general, wheat enriched for the greatest diversity of fungi, whereas vetch and clover were best for enrichment of AM fungi and oat for saprotrophs. Specific groups of fungi more abundant in wheat roots included members of the Sordariomycetes, mainly represented by the families Lasiosphaeriaceae, Magnaporthaceae and the order Pleosporales; whereas vetch recovered greater abundance of Hypocreales-like sequences, highly represented by the genus Ilyonectria. Within AM fungi differences in taxa recovery were observed between the orders Glomerales and Diversisporales across hosts, being these groups more abundant in wheat and vetch roots, respectively. From a fungal perspective, the direct benefits of the cover crop species (or species mix) in the cash crop will relate to the life history characteristics of the fungal communities preferentially colonizing each cover crop host.