Quantitative and cell type-specific transcriptional regulation of A-type cyclin-dependent kinase in Arabidopsis thaliana.
A-type cyclin-dependent kinase (CDKA) is an ortholog of yeast Cdc2/Cdc28p, and is assumed to have an essential function in plant growth and organogenesis. Previous studies revealed that its kinase activity is controlled by post-translational modifications, such as binding to cyclins and phosphorylations, but its transcriptional regulation is poorly understood. Here, we generated a promoter dissection series of Arabidopsis (Arabidopsis thaliana) CDKA;1, and used beta-glucuronidase (GUS) gene-fused reporter constructs for expression analyses in planta. The results revealed two types of transcriptional control in shoots: general quantitative regulation and cell type-specific regulation. We identified a promoter region that promotes CDKA;1 expression in the leaf epidermis, but not in the L1 layer of the shoot apical meristem. This region also directed abaxial side-biased expression, which may be linked to the adaxial/abaxial side specification. Another reporter construct showed that CDKA;1 expression in the inner layers of leaves is controlled by a distinct regulatory region in the promoter. These results suggest that the transcriptional regulation of CDKA;1 may play a key role in proper development of leaves by coordinating cell division and differentiation of different cell types.
Adachi
Sumiko
S
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan.
Nobusawa
Takashi
T
Umeda
Masaaki
M
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D018844:Cyclin-Dependent Kinases; D005966:Glucuronidase