Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis.
Plant steroid hormones, brassinosteroids (BRs), are perceived by a cell surface receptor kinase, BRI1, but how BR binding leads to regulation of gene expression in the nucleus is unknown. Here we describe the identification of BZR1 as a nuclear component of the BR signal transduction pathway. A dominant mutation bzr1-1D suppresses BR-deficient and BR-insensitive (bri1) phenotypes and enhances feedback inhibition of BR biosynthesis. BZR1 protein accumulates in the nucleus of elongating cells of dark-grown hypocotyls and is stabilized by BR signaling and the bzr1-1D mutation. Our results demonstrate that BZR1 is a positive regulator of the BR signaling pathway that mediates both downstream BR responses and feedback regulation of BR biosynthesis.
Wang
Zhi Yong
ZY
Howard Hughes Medical Institute and Plant Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
Nakano
Takeshi
T
Gendron
Joshua
J
He
Junxian
J
Chen
Meng
M
Vafeados
Dionne
D
Yang
Yanli
Y
Fujioka
Shozo
S
Yoshida
Shigeo
S
Asami
Tadao
T
Chory
Joanne
J
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins; D025461:Feedback, Physiological / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D059828:Plant Cells; D010944:Plants / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013256:Steroids / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; C454444:BZR1 protein, Arabidopsis; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D013256:Steroids