Comparative sensitivity of plant root meristems to acute gamma irradiation according to stationary phase cell distribution and DNA content

Thomas L. Rost
A. H. Sparrow and his coworkers have, in a long series of papers, formulated a broad generalization relating certain cellular characteristics to radio sensitivity for a wide range of organisms (Sparrow, Underbrink and Sparrow 1967, Underbrink, Sparrow and. Sparrow et al. (1965) pointed out that tolerance of species to chronic exposure of ionizing radiation is related to the size of genetic targets, and also to the average length of the mitotic cycle. Organisms with long cycle times and long
more » ... times and long periods in G2, for instance, would offer potential for greater radiation damage than organisms with short G2 duration and short cycle times. Yamakawa and Sparrow (1966) measured the radiosensitivity of pollen grains based upon dose-dependent pollen abortion and reported a linear relationship between interphase chromosome volume and radiosensitivity. Sparrow et al. (1968 ), Under brink et al. (1968 and Price et al. (1973) have expanded this generalization to many other organisms; as the interphase chromosome volume, or nuclear volume, increases, the radio sensitivity of the organisms also increases. Other correlations have been reported by Van't Hof and Sparrow (1963b) and Van't Hof (1964 , 1974a such as DNA content with mitotic cycle duration, and duration of S. Bennett (1973) summarized many studies which show a similar relationship between the duration of meiosis, its stages and nuclear DNA content. Bennett (1974) also examined the role nuclear characters play in morphogenesis. He drew correlations from the literature showing the relationship of DNA content (nucleotype) and many plant metabolic size and development characters. Van't Hof (1974b) discusses a property of plant root meristems whereby cells exposed to carbohydrate starvation become arrested according to a characteristic ratio of G1 and G2 nuclei. This condition known as stationary phase is species specific and may be induced by other forms of stress sources as well (Rost 1977) . In the current study we intend to compare the effect of acute irradiation at doses ranging from 100R to 1000R in four species with different stationary phase ratios. Two questions will be addressed: 1) Will the delay of entry of cells into
doi:10.1508/cytologia.47.743 fatcat:orzxiwwxkjdpbokceuolij62oa