Global drivers of obligate mycorrhizal symbionts diversification

Abstract

Arbuscular mycorrhizal fungi (AMF) are widespread microfungi that provide mineral nutrients to most land plants and form one of the oldest terrestrial symbioses. They have often been referred to as an “evolutionary cul-de-sac” for their limited ecological and species diversity. Here we use a global database of AMF to analyze their diversification dynamics in the past 500 million years (Myr). We find that AMF have low diversification rates. After a diversification peak around 150 Myr ago, they experienced an important diversification slowdown in the last 100 Myr, likely related to a shrinking of their suitable ecological niches. Our results clarify patterns and drivers of diversification in a group of obligate symbionts of major ecological and evolutionary importance. They also highlight a striking example of a diversification slowdown that, instead of reflecting an adaptive radiation as typically assumed, results from a limited ability to colonize new niches in an evolutionary cul-de-sac.

Best practices in metabarcoding of fungi: From experimental design to results

“…Based on 18S rRNA gene sequences, ascomycete and basidiomycete species belonging to different orders may display identical or near‐identical sequences, which render SSU unsuited for fungal DNA metabarcoding at species level. However, unicellular fungal lineages and Glomeromycota display greater SSU variation, although species‐level distinction in the latter group is not straightforward as most virtual taxa and morphospecies are >50 million years old (Bruns & Taylor, 2016; Perez‐Lamarque et al, 2020), which roughly corresponds to the age of genera in most other fungal groups. To improve taxonomic resolution and reproducibility of identified taxa, exact sequence variant (ESV; also referred to as amplicon sequence variant) approaches have been developed for inferring OTUs (Box 2).…”

Morphological and molecular identifications of three native arbuscular mycorrhizal fungi isolated from the rhizosphere of Elaeis guineensis and Jatropha curcas in Indonesia

“…However, due to the high degree of ITS variation within AMF species, it is difficult to find distinct features of closely related AMF species (Krüger et al 2012;Victorino et al 2020). Therefore, the SSU rRNA gene of AMF has been the best option to use for AMFspecific primers as it is less variability compared to ITS, is highly conserved, and has high specificity of the primer combination (Lee et al 2008;Lekberg et al 2018;Perez-Lamarque et al 2020).…”