Incompatibility systems in Podospora, and macro- and microscopic manifestations of het-B incompatibility.

(A) The different genetically defined het systems of P. anserina are shown. Allelic systems are given in blue and non-allelic systems in red. het-V is involved both in allelic and non-allelic interactions and is given in purple. Opposing arrows represent an incompatible interaction. Full arrowheads indicate normal fertility, open arrowheads indicate sexual incompatibility. The arrow direction represents the direction of the cross, with the arrow pointing from the male parent to the female parent in the cross (for example for the V/V1 interaction, the diagram denotes that a male V1 x V female cross shows sexual incompatibility while the opposite cross is fertile). In the s/S interaction, the dashed arrowhead denotes the spore-killing reaction occurring in S male x s female crosses and leading to specific abortion of S spores. B. Barrage reaction (incompatibility) but lack of sexual incompatibility between B1 and B2. The strains of the given genotypes were confronted on corn meal agar and grown for 6 days in the dark (upper panel). The same plate was imaged again after a week under constant illumination (lower panel). Full incompatibility genotypes for relevant loci are as follows: B1: het-B1, het-c2, het-d3, het-e4, het-r, het-V; B2: het-B2, het-c2, het-d3, het-e4, het-r, het-V; E1: het-B1, het-c1, het-d3, het-e1, het-r, het-V; RV1: het-B1, het-c2, het-d3, het-e4, het-R, het-V1. Mating type is designated with—and + symbols. Note that fructifications (perithecia) form at the B1/B2 interface indicating the absence of sexual incompatibility in contrast to the C/E and RV1/rV interactions that show partial or total sterility respectively. C. Microscopic observation of the confrontation zone between a B1 strain expressing GFP and a B2 strain expressing RFP. The presumed anastomosis sites are marked by an arrowhead and lysed cell with an asterisk. In upper and lower right end panels, the confrontation zone between a B1 strain expressing GFP and a B1 strain expressing RFP shows normal heterokaryotic cells expressing both fluorescent markers. Each panel is 140x110 μ in size.

(PPTX)