Unirradiated Embryos Research Articles

Nuove Prospettive Nello Studio dei Fattori che Controllano la Germinazione Dei Semi

Abstract New perspectives in the study of factors which control seed germination. — Seedlings of Triticum durum, cv. « Cappelli », coming from unirradiated embryos grafted on to irradiated endosperms (EM(u)/EN(i) of presoaked seeds (in distilled water for 24 h. at 20[ddot]C.) (treatment: X-rays, doses, 2,4,6,8,10 and 20 Kr), grow more than seedlings of control EM(u)/EN(u) (dose 0) (fig. 1). To have this reaction, it is necessary that the used seeds be after-ripe; at the various stages of seed ripening, be ginning from the milk stage, the phenomenon is not present. On this basis, the author has thought that a natural inhibitor occurs in the after-ripe endosperm of « Cappelli », which is neutralized or destroyed by X-rays. As an experimental demonstration, some trials have been made of growing wheat seedlings in Petri dish, on moistened (distilled water) filter paper, together with excised embryos or isolated endosperms (fig. 2): the after-ripe endosperm is able to depress the seedling growth (fig. 3). In t...

Cytological Aberrations Observed in Barley Embryos Cultured in Irradiated Potato Mash

As a basis for understanding the effects of radiation on plant and animal tissues, Ehrenberg et al. (1) studied, by means of electron spin resonance absorption, the free radicals produced when monosaccharides and disaccharides are exposed to ionizing radiation. They found that free radicals, which in many cases were quite stable in air, were formed, thereby indicating that in macromolecular systems secondarily formed energy-rich compounds such as peroxides may have a role in causing the observed radiobiological effect. Ahnstrim and Ehrenstein (2) and Westermark (3) have shown that dry solids on exposure to radiation may store large amounts of energy which act like radiation during dissolution. Either or both of these factors may be responsible for the mutations observed in Staphylococcus aureus cultured on irradiated substrate (4) and the chromosome aberrations induced when embryos of cereals such as wheat and barley are cultured in irradiated media (5, 6). In view of the obvious bearing of these investigations on the use of radiation as a tool in food preservation, there is need for critical studies on the effects of irradiated food material on biological tissues. Since the reports of Sparrow and Christensen (7, 8) that sprouting of potato tubers can be retarded or inhibited with X-rays and y-rays, there has been widespread interest in investigations relating to the use of radiation in the preservation of potatoes and other vegetables. It is clear now that a radiation dose of less than 20,000 r can effectively inhibit sprouting in potatoes and that this procedure may have practical application (9). Although extensive morphological, histological, physical, nutritional, and biochemical studies have been undertaken in potato tubers exposed to radiation, there are, as yet, no data on the effects of the irradiated material on the division and growth of cells of other unirradiated biological tissues. We hence undertook a study of mitosis in the root meristem of unirradiated barley embryos cultured in irradiated potato mash. Barley was chosen as the test material, since the first mitoses in germinating barley roots, unlike those of Vicia