Three redundant brassinosteroid early response genes encode putative bHLH transcription factors required for normal growth.
Brassinosteroids (BRs) are a class of polyhydroxylated steroids that are important regulators of plant growth and development. We have identified three closely related basic helix-loop-helix (bHLH) transcription factors, BEE1, BEE2, and BEE3, as products of early response genes required for full BR response. Comparison of the phenotypes of plants that overexpress BEE1 with bee1 bee2 bee3 triple-knockout mutant plants suggests that BEE1, BEE2, and BEE3 are functionally redundant positive regulators of BR signaling. Expression of BEE1, BEE2, and BEE3 is also regulated by other hormones, notably abscisic acid (ABA), a known antagonist of BR signaling. Reduced ABA response in plants overexpressing BEE1 suggests that BEE proteins may function as signaling intermediates in multiple pathways.
Friedrichsen
Danielle M
DM
Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Nemhauser
Jennifer
J
Muramitsu
Takamichi
T
Maloof
Julin N
JN
Alonso
José
J
Ecker
Joseph R
JR
Furuya
Masaki
M
Chory
Joanne
J
D000040:Abscisic Acid / Q000378:metabolism; D000595:Amino Acid Sequence; D000704:Analysis of Variance; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D060406:Brassinosteroids; D002777:Cholestanols / Q000494:pharmacology; D018257:Helix-Loop-Helix Motifs; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000494:pharmacology; D013256:Steroids / Q000378:metabolism*; D013260:Steroids, Heterocyclic / Q000494:pharmacology; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics*
D060406:Brassinosteroids; D002777:Cholestanols; D010937:Plant Growth Regulators; D013256:Steroids; D013260:Steroids, Heterocyclic; D014157:Transcription Factors; D000040:Abscisic Acid; C023623:brassinolide