Multiple genes evolved for fungal septal pore plugging identified via large-scale localization and functional screenings

Multicellular organisms exhibit cytoplasmic exchange using porous structures for cooperation among cells. Fungal multicellular lineages have evolved septal pores for this function. Interconnected hyphal cells possess the risk of wound-related cytoplasmic loss unless the septal pores are plugged. However, the gene evolution of regulatory mechanisms underlying fungal septal pore plugging remains poorly understood. To identify novel septal components, 776 uncharacterized proteins were identified using genomic comparisons between septal pore-bearing and -lacking ascomycete species. We then determined their subcellular localizations, and in total 62 proteins localized to the septum or septal pore. We analyzed the effects of deleting the encoding genes on septal pore plugging upon hyphal wounding. Of the 62 proteins, 23 were involved in regulating septal pore plugging. Here, using orthologous group and phylogenetic analyses, this study suggests that septal pore regulation has evolved either by co-option of preexisting genes or by Pezizomycotina-specific gene acquisition.