Fig. 1: Heterokaryon incompatibility (HI) represents a prophylactic cell death reaction in fungi, limiting exchanges between genetically distinct fungal colonies.
From: Regulated cell death in fungi from a comparative immunology perspective
Regulated cell death (RCD) occurs post-anastomosis – a cellular fusion process. The illustration shows a blue hyphal cell from one colony fusing with a red hyphal cell from a genetically distinct, incompatible individual. Generally, the newly formed heterokaryon is rapidly isolated from both colonies – symbolized by keylocks – by plugging the pores that connect adjacent cells in the hyphae. The HI cell death process is characterized by massive vacuolization, production of reactive oxygen species (ROS), and the formation of lipid droplets. Additionally, cell wall thickening and de novo septation occur—although these features are not depicted in the cartoon. Subsequently, the HI cell death culminates in plasma membrane shrinkage and rupture, releasing the cytoplasm of the dead fusion cells.
