George N. Bistis

DIKARYOTIZATION IN CLITOCYBE TRUNCICOLA

SUMMARY The process of dikaryotization in Clitocybe truncicola Peck was examined by phase-contrast microscopy. The first dikaryotic cells do not arise directly from the two homokaryotic cells that have fused but from homokaryotic cells some distance from the place of fusion. The intervening homokaryotic cells are severely disrupted and they appear to act as channels for the migrating, compatible nucleus. After a time, this nucleus ceases its migration and forms a dikaryotic association with one of the resident nuclei. From the cell containing this pair of nuclei the first dikaryotic hypha often arises. The first few conjugate divisions in this hypha are often marked by abnormal clamp connections and/or nuclear distributions. Eventually, however, the dikaryon stabilizes and later divisions are normal. During the past 45 years several partial descriptions of the cytology of dikaryotization in a number of different species of tetrapolar basidiomycetes have appeared. Both the methods used and the results reported differ radically. Lehfeldt (1923), Noble (1937) and Giesy and Day (1965) examined fixed and stained material. Buller (1931) and Lange (1966) examined living material, the former by light microscopy, the latter by phase-contrast microscopy. These accounts agree that the fusion of two compatible cells is the first step in dikaryotization; they disagree on the nature of the subsequent events. Lehfeldt (1923) found two distinct processes of dikaryotization among a group of tetrapolar basidiomycetes. In the Corticium serum type the first dikaryotic cells arise directly and presumably immediately

Fundamentals of Mycology

Fundamentals of mycology , Fundamentals of mycology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی