Plant mitosis promoting factor disassembles the microtubule preprophase band and accelerates prophase progression in Tradescantia.
The regulation of mitosis in higher plant cells has been investigated by microinjecting protein kinase from the metaphase-arresting (met1) mutant of Chlamydomonas. Biochemical characterization of this enzyme complex confirms the presence of a p34cdc2/cyclin B-like kinase. The enzyme was injected into living stamen hair cells of Tradescantia virginiana in which microtubules (MTs) were visualized using fluorescent analogue cytochemistry and confocal laser scanning microscopy. Microinjection of this p34cdc2/cyclin B-like kinase caused rapid disassembly of the preprophase band of MTs but not of interphase-cortical, spindle or phragmoplast MTs. Effects of the enzyme on the cytomorphology of live prophase cells were also monitored using video microscopy. We found that injection of this enzyme accelerated chromatin condensation and nuclear envelope breakdown. This indicates the presence and function in plants of an enzyme that can initiate nuclear division similar to the maturation or mitosis promoting factor (MPF) of animal cells. These studies provide the first direct evidence that the mitotically-active form of plant MPF can drive disassembly of preprophase band MTs, chromosome condensation and initiation of mitosis in plant cells.
Hush
J
J
School of Biological Sciences, University of Sydney, Australia.
Wu
L
L
John
P C
PC
Hepler
L H
LH
Hepler
P K
PK
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002452:Cell Count; D002696:Chlamydomonas / Q000737:chemistry / Q000235:genetics; D002843:Chromatin / Q000187:drug effects; D016200:Maturation-Promoting Factor / Q000494:pharmacology*; D008677:Metaphase / Q000187:drug effects; D008845:Microinjections; D018613:Microscopy, Confocal; D008870:Microtubules / Q000187:drug effects*; D009154:Mutation / Q000502:physiology; D009685:Nuclear Envelope / Q000187:drug effects; D059828:Plant Cells; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000187:drug effects / Q000201:enzymology; D011418:Prophase / Q000187:drug effects*; D008941:Spindle Apparatus / Q000187:drug effects
D002843:Chromatin; D010940:Plant Proteins; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor