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THE EFFECTS ON CHRONIC GAMMA RADIATION ON THE INTERNAL APICAL CONFIGURATIONS OF THE VEGETATIVE SHOOT APEX OF COLEUS BLUMEI
Author(s) -
Crockett Lawrence J.
Publication year - 1968
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1968.tb06970.x
Subject(s) - biology , apex (geometry) , shoot , tunica , botany , coleus , radiosensitivity , irradiation , physics , nuclear physics
Clonal plants of a bushy variety ‘Trailing Queen’ of Coleus blumei Benth. were exposed to 600–700 R per day for 28 days. Shoot apices of control and irradiated plants were studied microscopically. The normal vegetative shoot apex has two tunica layers and a corpus which is partly layered and partly composed of randomly divided cells. Five cytohistological zones were observed, including a cup‐shaped zone, imposed upon the tunica‐corpus relationships. Response to gamma radiation resulted in abnormal internal apical configurations. All irradiated shoots was found to have the same internal configurations. Only a single tunica layer broken by occasional periclinal divisions was observed. The cytohistological organization of irradiated apices was different from that seen in the normal shoot tips in that two zones were found. Evidence of a radiosensitivity gradient within the vegetative shoot apex was also observed. The possible significance of the results is discussed.