Genetic response ofAntirrhinum majus to acute and chronic plant irradiation
- 58 Downloads
Clonal lines ofAntirrhinum majus heterozygous for flower color have been used to study somatic mutations induced by irradiating plants with chronic gamma rays from cobalt-60 and acute X rays. Pink or white flecks and sectors of various sizes on the purple flowers are interpreted as resulting from mutational events at different times in flower development.
Acute X-ray treatment of pre-flowering stages caused no visible change in flowers opening prior to the 15th day thereafter. On the 16th to 19th days there was dense mottling, and by the 20th or 21st day numerous eight-cell mutant spots could be counted. The number of spots induced by 1,000 r of X rays was used to obtain a preliminary estimate of an average mutation rate for the three genes studied of 6.33×10−6 per cell per roentgen.
Chronic irradiation in a gamma radiation field and greenhouse showed a linear response of mutation rate to daily dose rate, the actual rate being subject to seasonal variation. There were occasional indications of non-linearity but further tests have failed to show any significantly higher mutagenic efficiency of dose rates below 6 r/day.
In plants removed from chronic gamma irradiation the frequency of mutation spots returns to the spontaneous level after about six weeks. The appearance, however, of mutant sectors on plants several months after exposure to both acute and chronic radiation indicates the induction of persistent genetic changes. Progeny tests of seeds and cuttings are planned to test the nature of these genetic events.
KeywordsDose Rate Gamma Irradiation Clonal Line Chronic Irradiation Average Mutation
Unable to display preview. Download preview PDF.
- Hoffmann, W.: Ergebnisse der Mutationszüchtung. In: Vorträge über Pflanzenzüchtung, p. 36–53. Land- und Forstwirtsch. Forschungsrat e. V., Bonn 1951.Google Scholar
- Konzak, C. F.: Genetic effects of radiation in higher plants. Quart. Rev. Biol.32, 27–45 (1957).Google Scholar
- MacKey, J.: Mutation breeding in Europe. In: Genetics in Plant Breeding, Brookhaven Symposia in Biol.9, 141–152 (1956).Google Scholar
- McClintock, B.: Intranuclear systems controlling geneaction and mutation. In: Mutation, Brookhaven Symposia in Biol.8, 58–71 (1956).Google Scholar
- Sparrow, A. H.: Somatic mutations induced in plants by treatment with X and γ radiation. Proc. 9. Internat. Congr. Gen. Caryologia (Pisa)6, Suppl., 1105–1106 (1954).Google Scholar
- Sparrow, A. H., andV. Pond: Some cytogenetic and morphogenetic effects of ionizing radiation on plants. In: Conference on Radioactive Isotopes in Agriculture, p. 125–139. U.S.A.E.C. Document No. TID 7512. For sale by Supt. of Documents, U. S. Govt. Printing Office, Washington 25, D. C. 1956.Google Scholar
- Sparrow, A. H., andW. R. Singleton: The use of radiocobalt as a source of gamma rays and some effects of chronic irradiation on growing plants. Amer. Naturalist87, 29–48 (1953).Google Scholar
- Stubbe, H.: Die Gene vonAntirrhinum majus. IV. Z. Vererbungslehre79, 401–443 (1941).Google Scholar