GROWTH INHIBITION, MITOTIC CYCLE TIME AND CELL NUMBER IN CHRONICALLY IRRADIATED ROOT MERISTEMS OF PISUM

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Radiation Botany

DOI:https://doi.org/10.1016/S0033-7560(63)80020-4· OSTI ID:4123023

Van't Hof, J.; Sparrow, A. H.

Seedlings of Pisum sativum were chronically irradiated with gamma rays from a Co/sup 60/ source at daily exposure rates sufficient to produce growth inhibition. Exposure rates of 500 and 1000 r/day reduced root growth by the fourth day. In order to determine the factor(s) that might be responsible for the reduced growth rate, the following measurements were made. the number of cells comprising the root meristem was determined daily for seven days; the percentage of aberrant cells at anaphase was scored after three days exposure; and the minimum mitotic cycle time for meristematic cells was established, also after three days of exposure. Cell counts showed an approximate reduction of 5, 25, and 45% compared to control on the third day of exposure at rates of 250, 500, and 1000 r per day. The minimum mitotic cycle time was measured by producing a tetraploid cell population with colchicine and noting the span of time between the production of this population and its initial appearance in the subsequent mitosis. These measurements indicated no change in the minimum cycle time of the cells in the irradiated meristems as compared to the unirradiated controls. Analysis of cells at anaphase showed an increase in the number of cells with broken chromosomes with increased exposure rate. Therefore, the reduction in growth observed in irradiated seedlings was attributed to the loss of reproductive integrity not due to a general slowing down of the cells' division rate but rather to genetic loss and/or unbalance and mitotic arrest of meristematic cells. (auth)

• Research Organization: Brookhaven National Lab., Upton, N.Y.
• NSA Number: NSA-18-005082
• OSTI ID: 4123023
• Report Number(s): BNL-6943
• Journal Information: Radiation Botany, Journal Name: Radiation Botany Vol. Vol: 3
• Country of Publication: United States
• Language: English

Related Subjects

AGE
ALKALOIDS
BIOLOGY AND MEDICINE
CHROMOSOMES
COBALT 60
CYTOLOGY
GAMMA RADIATION
GAMMA SOURCES
GENETICS
MERISTEM
MITOSIS
PHYSIOLOGY
PISUM SATIVUM
PLANTS
QUANTITATIVE ANALYSIS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
ROOTS
SEEDS
TISSUES
VARIATIONS