Overexpression of constitutive differential growth 1 gene, which encodes a RLCKVII-subfamily protein kinase, causes abnormal differential and elongation growth after organ differentiation in Arabidopsis.
To better understand genetic regulation of differential growth of plant organs, a dominant and semidwarf mutant, constitutive differential growth 1-Dominant (cdg1-D), was isolated utilizing the technique of activation tagging. cdg1-D showed pleiotropic phenotype including dwarfism, exaggerated leaf epinasty, and twisted or spiral growth in hypocotyl, inflorescence stem, and petiole. Hypocotyls of cdg1-D were longer than those of wild type under light conditions. The phenotype was caused by activation tagging of CDG1 gene that encodes a receptor-like cytoplasmic kinase of RLCKVII subfamily. When treated with high concentrations of brassinolide, light-grown wild-type seedlings showed long hypocotyls and strong leaf epinasty as observed in cdg1-D seedlings. Treatment of cdg1-D with brassinazole, a specific inhibitor of brassinosteroid (BR) biosynthesis, did not rescue the mutant phenotype. Gene expression of CONSTITUTIVE PHOTOMORPHOGENESIS AND DWARFISM involved in BR biosynthesis and phyB ACTIVATION-TAGGED SUPPRESSOR1 that inactivates BR was repressed and induced, respectively, in cdg1-D plants, suggesting constitutive activation of BR signaling in the mutant. CDG1 was expressed at a very low level in all the organs of the wild type tested. We isolated two independent intragenic suppressors of cdg1-D. However, they showed normal morphology and responded to BR in a similar manner to wild type. Taken together, CDG1 gene may interfere with signal transduction of BR when overexpressed, but is not an essential factor for it in the wild type.
Division of Biological Sciences, Graduate School of Environmental Earth Science, and Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
Hideki
H
Muto
Naoto
N
Yabe
Tadao
T
Asami
Koji
K
Hasunuma
Kotaro T
KT
Yamamoto
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013260:Steroids, Heterocyclic / Q000378:metabolism
D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; D017346:Protein Serine-Threonine Kinases; C023623:brassinolide