Several patches of white conidia were seen in green colonies of the duplication strain proA1 pabaA6 adE20 biA1;Dp(IR IIR)yA2, grown on 10(-2) M isonicotinic acid hydrazide; one with a mutation now designated wB1, has been analyzed.
A cross of the isolate to a master strain with yellow conidia and a marker on each of the eight linkage groups (MSF) yielded 683 white, 375 yellow and 337 green progeny, indicating a single gene mutation, epistatic to yA2/yA+. The heterokaryon with MSF bore white and yellow conidia; it gave a green diploid which, on haploidization, located wB1 to linkage group VII.
A heterokaryon with master strain E (also with a marker on each linkage group, including wA3 on II) had only white conidia and gave, as expected, a green diploid. White haploids from the latter, detectable as wA3, wB1 or wA3 wB1 by the segregation of other markers, were phenotypically indistinguishable.
Meiotic linkage was tested against only one linkage group VII marker, wetA6. The proportion of clearly-classifiable, non-wet progeny varied from perithecium to perithecium but the overall results suggested free, or nearly free, recombination between wB and wetA.