Ancient lineages of arbuscular mycorrhizal fungi provide little plant benefit

Abstract

Almost all land plants form symbiotic associations with arbuscular mycorrhizal fungi (AMF). Individual plants usually are colonized by a wide range of phylogenetically diverse AMF species. The impact that different AMF taxa have on plant growth is only partly understood. We screened 44 AMF isolates for their effect on growth promotion and nutrient uptake of leek plants (Allium porrum), including isolates that have not been tested previously. In particular, we aimed to test weather AMF lineages with an ancient evolutionary age differ from relatively recent lineages in their effects on leek plants. The AMF isolates that were tested covered 18 species from all five AMF orders, eight families, and 13 genera. The experiment was conducted in a greenhouse. A soil–sand mixture was used as substrate for the leek plants. Plant growth response to inoculation with AMF varied from − 19 to 232% and depended on isolate, species, and family identity. Species from the ancient families Archaeosporaceae and Paraglomeraceae tended to be less beneficial, in terms of stimulation plant growth and nutrient uptake, than species of Glomeraceae, Entrophosporaceae, and Diversisporaceae, which are considered phylogenetically more recent than those ancient families. Root colonization levels also depended on AMF family. This study indicates that plant benefit in the symbiosis between plants and AMF is linked to fungal identity and phylogeny and it shows that there are large differences in effectiveness of different AMF.

The effects of arbuscular mycorrhizal fungal species and taxonomic groups on stressed and unstressed plants: a global meta‐analysis

“…For example, in a recent comparison of several AMF species belonging to different lineages, it was shown that two species (i.e. Archaeospora europaea and Paraglomus laccatum ) belonging to basal lineages did not provide nutritional benefits to leek (Säle et al ., 2021). Our meta‐analysis showed overall positive effects of basal lineages on plant performance, although in Poaceae they did not differ from zero.…”

“…As in Säle et al . (2021), to test the link between AMF taxonomy and mycorrhizal functioning, we followed Oehl et al . (2011) for clade names.…”

Global drivers of obligate mycorrhizal symbionts diversification

“…We reported the highest speciation rates in Glomeraceae and Diversisporaceae. Speciation rates in Paraglomeraceae and Archaeosporaceae, which are thought to be less beneficial for the plants than the fast diversifying Glomeraceae and Diversisporaceae (Säle et al, 2021), were an order of magnitude lower. We can therefore speculate that good symbiotic abilities may favor diversification, although this remains to be tested in further investigations.…”

Analysing diversification dynamics using barcoding data: The case of an obligate mycorrhizal symbiont

“…Diversisporaceae (Säle et al, 2021), were an order of magnitude lower. We can therefore speculate that good symbiotic abilities may favour diversification, although this remains to be tested in further investigations.…”