Introduction

Mucoromycotina “fine root endophytes”: a novel molecular framework for mutualisms between plants and mushrooms?

The relationships between plants and arbuscular mycorrhizal (AM) fungus belonging to the Glomeromycotina clade are the most researched plant–fungal symbioses to date.

Thanks to developments in phylogenetics and microbial community profiling, a group of fungi that resemble AM fungi and form symbioses have been identified as belonging to the Mucoromycotina instead. These mysterious fungi are now referred to as “fine root endophytes” of the Mucoromycotina genus and may hold the key to unlocking the history of plant–fungal symbioses. The majority of our understanding of the mechanisms behind fungal symbiosis is derived from research utilizing AM fungus.