Glomeromycotina: what is a species and why should we care?

Abstract

Summary A workshop at the recent International Conference on Mycorrhiza was focused on species recognition in Glomeromycotina and parts of their basic biology that define species. The workshop was motivated by the paradigm‐shifting evidence derived from genomic data for sex and for the lack of heterokaryosis, and by published exchanges in Science that were based on different species concepts and have led to differing views of dispersal and endemism in these fungi. Although a lively discussion ensued, there was general agreement that species recognition in the group is in need of more attention, and that many basic assumptions about the biology of these important fungi including sexual or clonal reproduction, similarity or dissimilarity of nuclei within an individual, and species boundaries need to be re‐examined and scrutinized with current techniques.

Multiscale patterns and drivers of arbuscular mycorrhizal fungal communities in the roots and root‐associated soil of a wild perennial herb

“…These primers have often been used to assess the community composition of AM fungi (Öpik et al ., ; Davison et al ., ). Samples were sequenced at SciLifeLab/NGI (Solna, Sweden) on the MiSeq platform (Illumina Inc., San Diego, CA, USA), and sequences were clustered based on 99% similarity, a cutoff previously used in studies of AM fungal biogeographical patterns (Kivlin et al ., ; but see Bruns & Taylor, ; and Bruns et al ., ).To assess nonAM root‐associated fungi we used primers targeting the internal transcribed spacer (ITS) region using the primers fITS7 (Ihrmark et al ., ) and ITS4 (White et al ., ), which target a 250–450 bp fragment encompassing the entire ITS2 with flanking sequences in the 5.8 and large subunit genes. We followed the protocol of Clemmensen et al .…”

“…A global assessment of AM fungal communities showed low endemism, with the majority of AM taxa found on several continents (Davison et al ., ; but see Bruns & Taylor, ; and Bruns et al ., ). While this indicates that dispersal at a global scale does occur, it is generally thought that AM fungal communities are structured by local environmental filtering.…”

Arbuscular mycorrhizal fungi: intraspecific diversity and pangenomes

“…Better taxonomical definitions would also benefit our understanding of AMF ecological genomics. Critical issues surrounding AMF taxonomy have been raised recently by others (Bruns et al ., ), as species delineation is at the core of how we define populations. Conspecific isolates are expected to undergo anastomosis and exchange nuclei (Croll et al ., ; Sbrana et al ., ), thus, in addition to morphology and phylogenetics, species designation could also be supported by anastomosis experiments (Giovannetti et al ., ).…”

Sex, plasticity, and biologically significant variation in one Glomeromycotina species

“…The account of a recent workshop (at the 9 th International Conference on Mycorrhiza (ICOM 9), Prague 2017) ‘Glomeromycotina: what is a species and why should we care?’ by Bruns et al . (, in this issue of New Phytologist , pp. 963–967) summarizes the current state of knowledge on genetic variation, sexual reproduction, phylogeny and species concepts in these important plant symbionts.…”

“…Bruns et al . () pose the question ‘Glomeromycotina: what is a species and why should we care?’ Obviously, the question ‘What is a Glomeromycortina species?’ is important to taxonomists and for understanding the evolution of this fungal subphylum. However, the ‘why should we care?’ part of this question was not addressed at the workshop.…”