Recombination in other chromosomal regions than the interval subjected to selection, in lines of Neurospora crassa selected for high and for low recombination frequency

Recombination studies involving regions of the linkage groups (LG:s) I, II, III, IV, V and VI were performed in wild-type isolates of Neurospora crassa picked out from lines selected for high and for low frequency of second division segregation (SDS) for asco in the left arm of LG VI. Significant differences in recombination frequencies between high and low selection lines were obtained when proximal regions in the LG:s I, IV, V and the left arm of LG VI were scored, while no difference between lines could be established in the regions located in the LG:s II, III and in the right arm of LG VI. The correlation between SDS-frequencies for asco obtained with different asco tester strains was much stronger than the correlation between SDS-frequencies for asco and the recombination frequency in any of the other regions tested. This suggests that some of the genetic factors separating the recombination frequencies of the two selection lines operate mainly within the asco-centromere interval.