PHIALIDE ANALYSIS OF MITOTIC RECOMBINATION IN VERTICILLIUM

1. Families of conidia each containing one product of successive mitotic divisions were isolated from conidiophore phialides by micromanipulation. Previous observations on mitotic recombination in conidiophores were confirmed and extended. 2. Mitotic recombination can apparently occur in any nuclear division in phialides and alleles segregate randomly with respect to the phialide tip. 3. Limited data suggest that the frequency of mitotic recombination is greater in phialides than at the germination of conidia. 4. The autonomous action of a mycelial colour mutant made segregation of this marker during mycelial growth detectable. The implication of its observed segregations in relation to chromatid strandedness and mitotic crossing-over are discussed. No evidence of a delay (nuclear division) between mitotic crossing-over and marker segregation was found. Assuming that mitotic chromatids have a polyneme structure there was no indication that the subchromatid strands are resolved by mitotic crossing-over. © 1968 Springer-Verlag.