Ectopic expression of EFFECTOR OF TRANSCRIPTION perturbs gibberellin-mediated plant developmental processes.
The plant hormone gibberellin (GA) is known to modulate various aspects of plant cell differentiation and development. The current model of GA-mediated regulation is based on a de-repressible system and includes specific protein modification and degradation. HRT, a zinc finger protein from barley has been shown to have GA-dependent transcriptional repressing activity on the seed-specific alpha-amylase promoter [Raventos, D., Skriver, K., Schlein, M., Karnahl, K., Rogers, S.W., Rogers, J.C. and Mundy, J. 1998. J. Biol. Chem. 273: 23313-23320]. Here we report the characterization of a dicot homologue from Brassica napus (BnET) and provide evidence for its role in GA response modulation suggesting that this could be a conserved feature of this gene family. When BnET is ectopically expressed in either Arabidopsis or tobacco the phenotypes include dwarfism due to shorter internodes and late flowering, reduced germination rate, increased anthocyanin content and reduced xylem lignification as a marker for terminal cell differentiation. Transient expression in protoplasts supports the notion that this most likely is due to a transcriptional repression of GA controlled genes. Finally, histological analysis showed that in contrast to other GA deficient mutants the shorter internodes were due to fewer but not smaller cells, suggesting a function of BnET in GA-mediated cell division control.
Ellerström
M
M
Botanical Institute, Gothenburg University, Box 461, SE- 405 30 Gothenburg, Sweden.
Reidt
W
W
Ivanov
R
R
Tiedemann
J
J
Melzer
M
M
Tewes
A
A
Moritz
T
T
Mock
H-P
HP
Sitbon
F
F
Rask
L
L
Bäumlein
H
H
D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D029688:Brassica napus / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D003583:Cytokinins / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018525:Germination; D005875:Gibberellins / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000494:pharmacology; D008031:Lignin / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D018547:Plant Stems / Q000166:cytology / Q000235:genetics; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015032:Zinc / Q000378:metabolism
D000872:Anthocyanins; D003583:Cytokinins; D018076:DNA, Complementary; D005875:Gibberellins; D007210:Indoleacetic Acids; D010940:Plant Proteins; D008031:Lignin; D015032:Zinc