Basidiosporogenesis in Boletus Rubinellus II. Late Spore Development

ABSTRACT

The process of late basidiosporogenesis has been divided into two stages based on nuclear behavior and changes in wall layers and cytoplasm. During the first stage (Stage 5), post-meiotic nuclei migrated from the basidium into the spore followed by the major phase of lipid droplet transport. Mitosis occurred later in this stage. Extensive thickening occurred in one spore wall layer during Stage 5. In the last stage (Stage 6) the cytoplasm became dense, one of the sibling nuclei apparently migrated from each spore to the basidium and the wall layers were further modified. During Stage 5 the hilar appendix reached maximum thickness and the compartment within it was fully developed. The droplet associated with spore discharge was formed at early Stage 6 and was initially membrane-bound. Later the hilar and sterigmal plugs and abscission layer formed. The implications of the results for spore maturation and discharge are discussed.

Key Words:

• basidiosporogenesis
• Boletus
• mitosis
• spore discharge
• ultrastructure