II.24. Mutation spectra of eceriferum genes.
U. Lundqvist, Swedish Seed Association, Svalöf, Sweden, and D. von Wettstein, Institute of Genetics, University of Copenhagen, Ø. Farimagsgade 2A, DK-1353 Copenhagen K., Denmark.
To date 876 induced and 4 spontaneous eceriferum (cer) mutants have been localized by diallelic crosses to 59 loci. The distribution of the 880 mutants among the 59 cer loci is as follows:
The mutation spectra for the 20 most frequently mutated eceriferum loci are given below. For each of these loci the percentage of alleles induced by the different mutagens is given.
The survey reveals that locus cer-i and locus cer-t are mutated preferentially with densely ionizing radiations, whereas locus cer-zc is especially sensitive towards ethyleneimine. Interestingly, the loci cer-i and cer-t are closely linked on chromosome 7. If one wishes to mutate the genes cer-c, cer-u, cer-q, cer-za, cer-j, cer-w or cer-s sulfonates are the mutagens of choice. Locus cer-g is more easily mutated with ionizing radiations than chemical mutagens. It emerges that X-rays produce an unspecific mutation pattern, whereas neutrons, ethyleneimine and sulfonates hit certain genes more than others. The genes that are preferentially mutated by the latter three mutagens are, however, quite different ones. These results underline the importance of analyzing the genetic variation induced by individual mutagens, if one wants to evaluate their usefulness in plant breeding or their health hazards.
