DURATION OF CELL CYCLES IN CULTURED ROOTS OF CONVOLVULUS

摘要: A B S T R C The durations of the cell cycle in physiologically different regions meristem cultured roots Convolvulus arvensis were determined by metaphase-accumulation technique involving colchicine. root cap increases from 13 hr actively dividing initials first tier to 155 slowly tiers 2-4 an indeterminate value for derivatives columella. times cells central cylinder and cortex are 21 27 hr, respectively. quiescent center have a estimated 420 hr. duration these is discussed relation increased G1 or non-dividing cells. possible regulation division synthesis cell-division factor also discussed. EARLY STUDIES on meristems intact plants yielded average values total elapsed time one mitosis next whole meristem. These studies did not consider differences populations within apex which might be distinct another. Then Clowes (1956) showed that region infrequently cells, he called center, existed close proximity rapidly gave rise apical Triticum Zea. Thereafter, attention shifted determination cell-cycle attempt understand how differential rates influenced development maintenance organized (1961) length initials, stele seedling Zea mays two experimental techniques; namely, continuous labelling with tritiated thymidine, metaphase accumulation He reported had shortest (12 hr), while longest (239 hr). 25-28 48-55 Using pulse-labelling (1965) found stelar was 14 22 Also, using pulse