This study analyzed the septal ultrastructure of dolipores and parenthesomes across 13 basidiomycete fungal species from eight different orders using electron microscopy and mathematical analysis. Rather than supporting previous proposals of two distinct dolipore size types, the researchers found a continuum of dolipore sizes. Measurements were taken on nine different structural parameters, including pore diameter, dolipore length, and parenthesome thickness. Cluster analysis using Ward's method revealed that species with non-perforate parenthesomes formed a distinct group of smaller structures, while species with perforate parenthesomes showed intermediate to large sizes. A strong positive correlation existed between most measured parameters, indicating that as dolipore size increased, most other structural features increased proportionally. The parenthesome bridge width between holes remained relatively constant regardless of hole size. The authors propose that dolipore modifications have phylogenetic significance and suggest a possible evolutionary pathway for dolipore/parenthesome development across basidiomycete groups, indicating these structures may be useful taxonomic markers.

Key findings

• A continuum of dolipore sizes exists across basidiomycetes rather than two distinct size-types, with species possessing non-perforate parenthesomes forming a smaller, distinct group
• Strong positive correlations exist between most measured septal parameters (r = 0.809-0.993), indicating coordinated size increases across structural features
• Parenthesome bridge width between holes remains constant at approximately 53 nm regardless of hole diameter, suggesting structural constraints on this dimension
• Cluster analysis separates species by dolipore characteristics in patterns that correlate with taxonomic classification and evolutionary relationships among basidiomycete orders