Kreuzungs-Analyse Sorbose-resistenter Mutanten von Neurospora crassa

Summary

After treatment of the conidia of Neurospora crassa with nitrous acid 19 of the resulting mutants were selected for their resistance to sorbose, an agent which has a toxic effect on the wild type. The selected sorbose resistant mutants were analyzed genetically by crossing them with tester strains containing known markers. Mutational sites were thus found to be located on at least 5 of the full complement of 7 linkage groups. 9 sites were found to be located on the left arm of linkage group VI near the ylo-marker. These were so far not separable by recombinational analysis and therefore seem to represent a single gene-locus (A). Other sorbose resistant sites were mapped on linkage groups I, III (gene C), V and VII (gene B). Another site which has not yet been definitely located is not closely linked to any of the aforementioned. One site each on linkage groups I and VI were mapped more precisely by means of 3-point crosses. These crosses permitted the location of these sites of sorbose resistance in regard to neighbouring markers. From these crosses it is concluded that the mutation of any 1 of at least 6 different chromosomal genes can cause the formation of a sorbose resistant phenotype. The mutation of any 1 of 4 of these genes could result in a mutant with an altered sorbose permease system or containing a suppressor which decreases the efficiency of the permease system.