VIABLE MUTANTS INDUCED IN BARLEY BY IONIZING RADIATIONS AND CHEMICAL MUTAGENS

Abstract

Genetic effects of ionizing radiations and chemical mutagens, especially with regard to the induction of viable mutants, were compared in barley. The chief mutagens used consisted of neutron and x irradiation, as well as treatments with glycidol, ethyleneimine, and ethyl methanesulfonate. Greenhouse mutants (chlorophyll mutants) amounted to 4000 cases in the years l958-l960. Field aberrations consisted of 2400 chlorophyll mutants, 650 dwarfs and other lethals, 5200 cases of so-called translocation sterility, and more than I000 cases of viable mutants. The total sum of X/sub 2/ aberrations, analyzed in the field, was 9300, in circa 2l500 spike progenies. Neutrons and x rays generally produce rates of greenhouse mutations up to 8 or 10%, or under special experimental con ditions up to 13 or 14%. Using ethyleneimine, rates of 25 to 30% are reached and with ethyl methanesulfonate, rates of 50 to 60%. The ratios of offspring showing translocation sterility to offspring with viable mutants are high applying neutrons and x rays, but low applying ethyleneimine and ethylmethanesulfonate. Ethyleneimine is especially efficient in inducing rare morphological mutants. In general, viable mutants are followed to the X/sub 3/ generation, Problems relating to the capacity of radiations and chemicals in causing specific gene mutationsmore » are briefly discussed. (P.C.H.)« less