Dear Colleagues,

Fungi are able to form somatic chimeras. In that aspect, they resemble other life forms such as marine colonial organisms or myxomycetes which also need to distinguish somatic intraspecific self from non-self. Both ascomycete and basidiomycete filamentous fungi have developed genetic systems that control fusion with conspecifics. Generally, but not always, outcomes of fusion events between distinct individuals are controlled at the post-fusion stage, and incompatibility between the involved individuals results in programmed cell death of the mixed fusion cells. When characterized, the genetic loci that define compatibility types have been found to be highly polymorphic in wild populations and subject to positive Darwinian selection and balancing selection.

Over the last decade or so, characterization of the genes controlling somatic non-self recognition in a few model fungal species has revealed that several of the molecular players are related to genes and pathways controlling immunity, symbiosis, and programmed cell death (PCD) in other kingdoms—notably in metazoans and plants. This trend is for instance illustrated by the fact that several fungal incompatibility genes encode NOD-like receptors. It has been proposed that fungal allorecognition genes evolve by exaptation, drawing from an existing toolbox corresponding to genes with other, more general functions in non-self recognition, PCD, and defense.

This Special Issue will be dedicated to studies bearing on non-self recognition and PCD in the context of allorecognition, but with the aim of also widening the focus to related topics such as the regulation of symbiosis, organismal defense, and immunity in fungi. We intend with this Special Issue to frame the evolutionary and mechanistic aspects of fungal incompatibility within this larger picture. As interesting comparison points, studies on allorecognition in non-fungal organisms such as myxomycetes will also be highly welcome. 

Dr. Sven J. Saupe
Guest Editor

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• non-self recognition
• fungi
• biotic interactions
• immunity
• organismal defense
• symbiosis