Changes in Sensitivity of Maize Chromosomes to X Rays During Seed Germination
Changes in the radiosensitivity of maize seeds during early stages of germination were studied by means of somatic-mutation techniques. Seeds heterozygous for the yg2 (yellow-green) locus were irradiated with 800 r of x rays after soaking in running tap water up to 42 hr. Yellow-green sectors, representing mutations affecting the dominant yg2 locus, in leaves 4 and 5 of seedling plants were used as a criterion of radiosensitivity. The frequency of soniatic sectors was virtually nil for dry seed and for seeds soaked up to 16 hr. Sector frequencies underwent a marked (9- to 15-fold) rise from 16 to 28 hr, reached a plateau of sensitivity and subsequently declined. Manometric studies were conducted on seeds soaked under the same conditions as those irradiated. The rate of oxygen consumption rose rapidly from 0 to 7 hr, remained essentially constant from 7 to 16 hr, then underwent an approximately 2-fold increase from 16 to 24 hr, after which the rate of progressive increase was retarded. The fact that the marked rise in frequency of x-ray-induced somatic sectors coincided with the major increase in oxygen consumption suggests that radiosensitivity of soaked seeds is conditioned by metabolic changes during seed development. Changes in radiosensitivity that followed attainment of peak sector frequencies were apparently governed by factors that influenced the rate of seed development.
- Research Organization:
- Brookhaven National Lab., Upton, N.Y.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-015650
- OSTI ID:
- 4755792
- Journal Information:
- American Journal of Botany, Vol. 49, Issue 5; Other Information: Orig. Receipt Date: 31-DEC-63; ISSN 0002-9122
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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