Radiation Probes of Maize Meristems
This paper reviews ways that irradiation of dry seeds in maize can be used to gain information about the stem apex and leaf primordia. For the most part the experiments were originally designed to investigate the biological effectiveness of different kinds of radiation; however, they are discussed here as a means of elucidating properties of meristems. Deuteron microbeam experiments were carried out to study the effect of irradiating only specific parts of the dormant embryo, rather than the whole seed. This was accomplished with a deuteron beam of sufficiently narrow width to localize the irradiation.16 As a consequence, a particular region, primordium or meristematic area could be marked in the embryo by the damage produced or the mutations induced, then traced by effects observed in the developed seedling. The purpose of reporting experiments on comparative responses to x rays vs. neutrons in the context of this conference is to call attention to the consistent and quantitatively predictable performance of the meristem during recovery from various levels of genetic damage inflicted by two different radiation probes of the seed embryo. Observations showing different radiation sensitivities for different embryonic leaves were used to analyze differences in size of nuclei and constituent chromosomal segments in leaf primordial cells.
KeywordsLeaf Primordia Relative Biological Effectiveness Brookhaven National Laboratory Fission Neutron Radiation Probe
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