Figure 3

Characteristics of heterokaryon. (a) Colony morphology of the successive cultures of heterokaryon TdRBP1-Het1 on PDAmb and PDAmb supplemented with hygromycin B. (b) Estimated ratio of two conidia types from TdRBP1-Het1. TdRBP1-Het1 cultures were maintained by successive transfers on PDAmb plates and successive transfers on selective PDAmb plates containing hygromycin B for more than 3 months. Conidia were collected from the transferred plates every week up to 20 weeks (T1–T20), and colonies from every fifth passage were selected for conidia analysis. In all, 100 conidia per plate, as counted by a hemacytometer, were spread on PDAmb media, and then the number of CFUs was determined. The number of CFUs represents the number of conidia containing wild-type nuclei. The wild-type EP155/2 is included as a control for spore counts and viability of freshly harvested conidia. (c) Microscopic observation of temporal stages in conidial germination of the putative CpRbp1-null mutant. The incubation times are indicated above the panel. Appearance of gigantic spherical cells is indicated in inlets of the corresponding stages. The strains used to harvest conidia, indicated on the left, were the wild-type EP155/2 (WT) and heterokaryotic CpRbp1-null mutant (TdRBP1-Het1) strains. Scale bar = 50 μm. (d) Colony morphology of CHV1-infected heterokaryons. Strains are indicated at the bottom of the panel. Virus-free and virus-infected isogenic strains are indicated in the upper and lower panels, respectively.