COMPARISON OF COMPLEMENTATION AND GENETIC MAPS OF CLOSELY LINKED NONALLELIC MARKERS ON LINKAGE GROUP I OF NEUROSPORA CRASSA

Homology tests between ad-3IR mutations and various strains carrying markers with known biochemical requirements or markers resulting from mutation of genes with unknown functions have been used to construct a complementation map of that part of Linkage Group I immediately adjacent to the ad-3 region. A comparison with the genetic map derived from intercrosses of some of the same markers indicates the same order of genes on both maps. The present homology tests provide a more detailed mapping of the ad-3IR mutations and show that many of them cover other known biochemical loci in the immediately adjacent regions. Both ad-3AIR and ad-3BIR mutations can cover a maximum of about 4.3 map units. The longest deletions in this region are a minimum of 8.7 map units. Present data indicate a minimum of four genes with unknown functions in the X region between the ad-3A and ad-3B loci. The map distance of 0.25 map unit for the X region suggests that there is a minimum of 16 genes per map unit. When this calculation is applied to map distances in the regions proximal to the ad-3A locus and distal to the ad-3B locus, this region of Linkage Group I emerges as a vast unknown rather than as the well-mapped region that it might appear to be at first glance. © 1966.