NUCLEAR PHENOMENA IN THE BASIDIUM OF CERATOBASIDIUM PRATICOLUM (KOTILA) OLIVE

Abstract

The nuclear phenomena in the basidium of Ceratobasidium praticolum (Pellicularia praticola), studied by the Giemsa technique, are described and illustrated with photographs. The cells of the vegetative hyphae are multinucleate and those of the hymenia binucleate. Before fusion the two nuclei in the young basidium become closely adjacent, and their chromosomes are differentiated as elongated threads in two distinct groups. After the association of the karyolymph of the two nuclei, the chromosomes come into contact and pair. The diploid nucleus then undergoes meiosis. The haploid chromosome number is about six, with six bivalents present at the first meiotic (disjunctional) division. Apparent chromatid bridges were observed at anaphase I. The second meiotic division is equational. The spindle axis during both these divisions may be longitudinal, transverse, or oblique. The mature basidium has four nuclei which migrate through sterigmata into the basidiospores. Most of the basidiospores are uninucleate when young, but become binucleate at maturity. The basidiospore germinates by repetition or directly by a germ tube. In either case coenocytic growth is produced which, upon further development, is divided into multinucleate hyphal cells by the formation of cross septa.