Nuclear Distribution in Metarrhizium Anisopliae

SUMMARYThe distribution of nuclei in the entomogenous fungus, Metarrhisium anisopliae, in culture, was studied by using Giemsa stain and light microscopy. Conidiophores initially are uninucleate. All the nudei in conidia produced on a conidiophore (in basipetal succession) are derived therefore from one progenitor. Mature conidia are typically uninucleate; during their germination the nucleus apparently divides and one daughter nucleus migrates into the germ tube, while the other remains in the spore. Usually a conidium forms a single germ tube from one polar area. Hyphal cells are mostly uninucleate but some cells contain two or, occasionally, more nuclei. Anastomoses, and presumably nuclear migrations, are common between conidia, conidia and germ tubes, and hyphae. The implications of the nuclear distribution and anastomoses are considered in relation to mechanisms of variation in the fungus.