A low content in zeatin type cytokinins is not restrictive for the occurrence of G1/S transition in tobacco BY-2 cells.
Theories on the importance of cytokinins in G1/S transition control are manifold and contradictory. By establishing a double A(phi-PZ block, maximal synchronization of a BY-2 suspension culture was obtained to investigate the effect of cytokinin depletion on G1/S transition. Lovastatin was used as a specific inhibitor of cytokinin biosynthesis. Flow cytometry showed that the G1/S transition occurred regardless of the cytokinin drop. This observation indicates an extremely low dose requiry for that stage of the cell cycle. It is very likely that precisely the downregulation of zeatin type cytokinins matters for the G1/S transition to occur, since cytokinin addition at early G1 blocked the cycle at G1/S.
Laureys
F
F
Department of Biology, Universiteit Antwerpen, Wilrijk, Belgium.
Smets
R
R
Lenjou
M
M
Van Bockstaele
D
D
Inzé
D
D
Van Onckelen
H
H
D016590:Aphidicolin / Q000494:pharmacology; D001549:Benzamides / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D008148:Lovastatin / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects; D010947:Plants, Toxic; D016196:S Phase; D014026:Nicotiana / Q000378:metabolism*; D015026:Zeatin / Q000378:metabolism* / Q000494:pharmacology
D001549:Benzamides; C001059:pronamide; D016590:Aphidicolin; D015026:Zeatin; D008148:Lovastatin