Binucleate Rhizoctonia: Diversity, Pathogenicity and Potential as Biological Control Agents

The genus Ceratobasidium comprises individuals that are filamentous fungi whose anamorphic phase includes binucleate Rhizoctonia (BNR). These microorganisms are soil dwellers and can be found in agricultural areas worldwide. Notably, BNR isolates have gained more interest due to their dual role in interactions with plants; while some isolates behave as aggressive pathogens, others demonstrate potential to promote plant growth and/or act as biocontrol agents. The symptoms caused by pathogenic BNR isolates can vary according to the anastomosis group and the host plant and include damping‐off, root rot, collar rot and shoot blight. In contrast, nonpathogenic strains have been explored for their ability as biocontrol agents acting by mycoparasitism, competition or by inducing systemic resistance in plants. In addition, some BNR can promote plant growth or behave as mycorrhiza. Given this functional duality, this literature review aims to summarise the current knowledge on BNR, addressing aspects from genetic diversity to the mechanisms that define its action as a pathogen or beneficial organism. By gathering and analysing this information, this review seeks to contribute to a deeper understanding of the ecological and functional complexity of this group of microorganisms, whose ambivalent nature is still poorly understood but of great relevance for phytopathology.