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SIAMESE, a Plant-Specific Cell Cycle Regulator, Controls Endoreplication Onset in Arabidopsis thaliana.

Authors :
Churchman, Michelle L.
Brown, Matthew L.
Kato, Naohiro
Kirik, Viktor
Hülskamp, Martin
Inze, Dirk
De Veylder, Lieven
Walker, Jason D.
Zhengui Zheng
Oppenheimer, David G.
Gwin, Taylor
Churchman, Jason
Larkin, John C.
Source :
Plant Cell; Nov2006, Vol. 18 Issue 11, p3145-3157, 13p, 4 Color Photographs, 2 Diagrams, 1 Chart, 2 Graphs
Publication Year :
2006

Abstract

Recessive mutations in the SIAMESE (SIM) gene of Arabidopsis thaliana result in multicellular trichomes harboring individual nuclei with a low ploidy level, a phenotype strikingly different from that of wild-type trichomes, which are single cells with a nuclear DNA content of ∼16C to 32C. These observations suggested that SIM is required to suppress mitosis as part of the switch to endoreplication in trichomes. Here, we demonstrate that SIM encodes a nuclear-localized 14-kD protein containing a cyclin binding motif and a motif found in ICK/KRP (for Interactors of Cdc2 kinase/Kip-related protein) cell cycle inhibitor proteins. Accordingly, SIM was found to associate with D-type cyclins and CDKA;1. Homologs of SIM were detected in other dicots and in monocots but not in mammals or fungi. SIM proteins are expressed throughout the shoot apical meristem, in leaf primordia, and in the elongation zone of the root and are localized to the nucleus. Plants overexpressing SIM are slow-growing and have narrow leaves and enlarged epidermal cells with an increased DNA content resulting from additional endocycles. We hypothesize that SIM encodes a plant-specific CDK inhibitor with a key function in the mitosis-to-endoreplication transition. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
10404651
Volume :
18
Issue :
11
Database :
Complementary Index
Journal :
Plant Cell
Publication Type :
Academic Journal
Accession number :
23641359
Full Text :
https://doi.org/10.1105/tpc.106.044834