DFL1, an auxin-responsive GH3 gene homologue, negatively regulates shoot cell elongation and lateral root formation, and positively regulates the light response of hypocotyl length.
A novel dominant mutant designated 'dwarf in light 1' (dfl1-D) was isolated from screening around 1200 Arabidopsis activation-tagged lines. dfl1-D has a shorter hypocotyl under blue, red and far-red light, but not in darkness. Inhibition of cell elongation in shoots caused an exaggerated dwarf phenotype in the adult plant. The lateral root growth of dfl1-D was inhibited without any reduction of primary root length. The genomic DNA adjacent to the right border of T-DNA was cloned by plasmid rescue. The rescued genomic DNA contained a gene encoding a GH3 homologue. The transcript was highly accumulated in the dfl1-D. The dfl1-D phenotype was confirmed by over-expression of the gene in the wild-type plant. The dfl1-D showed resistance to exogenous auxin treatment. Moreover, over-expression of antisense DFL1 resulted in larger shoots and an increase in the number of lateral roots. These results indicate that the gene product of DFL1 is involved in auxin signal transduction, and inhibits shoot and hypocotyl cell elongation and lateral root cell differentiation in light.
Nakazawa
M
M
Plant Function Exploration Team, Plant Functional Genomics Research Group, RIKEN, Genomic Sciences Center, 2-1 Hirosawa, Wako 351-0198, Japan. miki@postman.riken.go.jp
Yabe
N
N
Ichikawa
T
T
Yamamoto
Y Y
YY
Yoshizumi
T
T
Hasunuma
K
K
Matsui
M
M
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins; D001483:Base Sequence; D017931:DNA Primers; D004269:DNA, Bacterial; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development*; D018520:Plant Shoots / Q000254:growth & development*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology
D029681:Arabidopsis Proteins; C425524:DFL1 protein, Arabidopsis; D017931:DNA Primers; D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; C036483:T-DNA