The efflux kinetics of 86Rb from 24 hr preloaded Allium cepa cv. Evergreen Long White Bunching root tip cells through the first 120 hr of germination have been documented. Estimates of the percent of isotope, the calculated amount present and the halftime of efflux of the three root cell compartments present were made. Of the total isotope present the % in the vacuole decreased from maxima of 64% to 40% with germination time, while the % of the isotope in the cytoplasm remained uniform near 39%. The free space increased maximally throughout germination to 20% by 120 hr. Rb content, based on specific activity calculations, of the slowest, intermediate and fastest compartments was seen to rise from low levels at 52 hr germination toward maximal values by 96 hr. Speculation as to when a germinating root becomes functionally mature was attempted by comparing the times of onset of major macromolecule synthesis (DNA, RNA, protein) to that of maximal Rb content. Stable mitotic and DNA synthetic indices occurred at the 10 mm (72 hr) stage with the initiation of major macromolecules syntheses occurring prior to 2 mm (40 hr). 86Rb efflux data suggests that the compartments do not contain maximal amounts until the 22 mm (96 hr) stage.
|Original language||English (US)|
|Number of pages||8|
|Journal||Plant and Cell Physiology|
|State||Published - Jun 1 1979|
ASJC Scopus subject areas
- Plant Science
- Cell Biology