Radiosensitivity and Nuclear Volume in the Gymnosperms

摘要

The sensitivities to acute cobalt-60 gamma radiation of five species of gymnosperms were studied. The species were Pinus elliotti, Pinus palustris, Juniperus conferta, Podocarpus macrophylla, and Zamia floridana. The nuclear and interphase chromosome volumes (nuclear volume divided by chromosome number) were calculated from measurements of soot meristematic nuclei for each species. The plants, which were 1 to 2 year seedlings or 1 year old rooted cuttings, received acute radiation, taking care to shield the roots and thus simulate irradiation under natural growing conditions. The Gymnosperms are a very radiosensitive group of plants; the 50 percent lethal doses (LD50) for the species studied ranged from 500 to 760R. The correlation between radiosensitivity and nuclear (or interphase chromosome) volume for the species studied agreed quite well with values obtained from other acutely irradiated woody species. For an untested species, determination of interphase chromosome volume will permit fairly accurate prediction of the LD50 dose to be expected. (Author)