A basic helix-loop-helix transcription factor regulates cell elongation and seed germination.
Plants are sessile and rely on a wide variety of growth hormones to adjust growth and development in response to internal and external stimuli. We have identified a gene, designated NAN, encoding a basic helix-loop-helix (bHLH) transcription factor that regulates cell elongation and seed germination in plants. NAN has an HLH motif in its C-terminal region but does not have any other discernible homologies to bHLH proteins. A bipartite nuclear localization signal is located close to the HLH motif. An Arabidopsis mutant, nan-1D, in which NAN is activated by the insertion of the 35S enhancer, exhibits growth retardation with short hypocotyls and curled leaves. It is also characterized by reduced seed germination and apical hook formation, symptomatic of GA deficiency or disrupted GA signaling. The phenotypic effects of nan-1D were increased by treatment with paclobutrazol (PAC), an inhibitor of gibberellic acid (GA) biosynthesis. NAN is constitutively expressed throughout the life cycle. Our observations indicate that NAN has a housekeeping role in plant growth and development, particularly in seed germination and cell elongation, and that it may modulate GA signaling.
Graduate School of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea.
Jin-A
JA
Kim
Misun
M
Lee
Youn-Sung
YS
Kim
Jae-Chang
JC
Woo
Chung-Mo
CM
Park
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000502:physiology; D018525:Germination / Q000187:drug effects / Q000502:physiology*; D005875:Gibberellins / Q000502:physiology; D018257:Helix-Loop-Helix Motifs / Q000502:physiology*; D008969:Molecular Sequence Data; D010641:Phenotype; D018517:Plant Roots / Q000737:chemistry; D018520:Plant Shoots / Q000737:chemistry; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000096:biosynthesis / Q000502:physiology*
D029681:Arabidopsis Proteins; D005875:Gibberellins; C504900:Nan-1D protein, Arabidopsis; D014157:Transcription Factors; C007842:gibberellic acid