G2-and early-M-specific expression of the NTCYC1 cyclin gene in Nicotiana tabacum cells.
We have previously reported the isolation of a cDNA encoding a mitotic cyclin, NTCYC1, from a tobacco cell suspension library. Here we describe the expression patterns of NTCYC1 and of Ntsuc1, a suc 1 plant homologue, in synchronized tobacco cell suspensions. Furthermore, the expression pattern of this cyclin is compared to that of Ntcdc2-1, a Nicotiana tabacum homologue of cdc2. While no NTCYC1 transcript was detected in cells synchronized in the G1 and S phases, NTCYC1 expression was observed in late G2 and early M phases, disappearing in the G1' of a new cell cycle. On the other hand, Ntsuc1 and Ntcdc2-1 exhibited a constitutive expression during the cell cycle. A functional analysis performed by microinjecting NTCYC1 mRNA into immature Xenopus oocytes, indicates that NTCYC1 could participate in the control of the G2/M transition in plant cells. Subsequently NTCYC1 expression was used to assess the status of mesophyll cells in expanded leaves of N. tabacum. Depending on leaf position along the shoot axis, a large population of mesophyll cells appeared with a 4C DNA content, suggesting a G2 arrest. It was found that leaves with such a population also contained high levels of NTCYC1 transcripts. With respect to these results concerning a naturally occurring G2-arrested cell population, the regulation of NTCYC1 expression in planta is discussed.
Qin
L X
LX
Institut de Biotechnologie des Plantes, Université Paris-Sud, Plateau du Moulon, Orsay, France.
Perennes
C
C
Richard
L
L
Bouvier-Durand
M
M
Tréhin
C
C
Inzé
D
D
Bergounioux
C
C
D000595:Amino Acid Sequence; D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D018797:Cell Cycle Proteins; D016213:Cyclins / Q000737:chemistry / Q000235:genetics*; D005434:Flow Cytometry; D016195:G2 Phase; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008540:Meiosis; D008938:Mitosis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology; D010940:Plant Proteins; D010947:Plants, Toxic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014981:Xenopus
D018797:Cell Cycle Proteins; D016213:Cyclins; C103694:NTCYC1 protein, Nicotiana tabacum; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D016590:Aphidicolin