THE QUIESCENT CENTRE IN ROOT MERISTEMS OF VICIA FABA AND ITS BEHAVIOUR AFTER ACUTE X-IRRADIATION AND CHRONIC GAMMA IRRADIATION
Rates of mitosis in four regions of the meristem of Vicia faba were determined by accumulating metaphases in normal and irradiated roots. In normal roots there is a quiescent centre with cells dividing an average of once every 200-300 hr. The stelar cells divide about once every 30 hr and the cap initials a littie more slowly. Three days after receiving an acute dose of 360 rad the duration of the mitotic cycle (T) lengthens to 95 hr in the stele immediately above quiescent centre, to 40 hr in the stele at 250 from the pole, and to 95 hr in the cap initials. At the same time T falls to 65 hr in the quiescent centre and reaches a minimum of 38 hr at seven days after irradiation. By this time the other regions have begun to recover their normal rates of mitosis. After fourteen days of continuous irradiation at 2.28 rad/hr values of T are similar to those found shortly after acute irradiation; that is, rates of mitosis are more uniform than in normal meristems. These changes in rates of mitosis are discussed in relation to the growth rates of the roots and the reorganization of the meristem. (auth)
- Research Organization:
- Oxford Univ.
- NSA Number:
- NSA-17-023146
- OSTI ID:
- 4725834
- Journal Information:
- Radiation Botany, Vol. Vol: 3; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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