RAV-Like1 maintains brassinosteroid homeostasis via the coordinated activation of BRI1 and biosynthetic genes in rice.
Temporal and spatial variation in the levels of and sensitivity to hormones are essential for the development of higher organisms. Traditionally, end-product feedback regulation has been considered as the key mechanism for the achievement of cellular homeostasis. Brassinosteroids (BRs) are plant steroid hormones that are perceived by the cell surface receptor kinase Brassinosteroid Insensitive1. Binding of these hormones to the receptor activates BR signaling and eventually suppresses BR synthesis. This report shows that RAVL1 regulates the expression of the BR receptor. Furthermore, RAVL1 is also required for the expression of the BR biosynthetic genes D2, D11, and BRD1 that are subject to BR negative feedback. Activation by RAVL1 was coordinated via E-box cis-elements in the promoters of the receptor and biosynthetic genes. Also, RAVL1 is necessary for the response of these genes to changes in cellular BR homeostasis. Genetic evidence is presented to strengthen the observation that the primary action of RAVL1 mediates the expression of genes involved in BR signaling and biosynthesis. This study thus describes a regulatory circuit modulating the homeostasis of BR in which RAVL1 ensures the basal activity of both the signaling and the biosynthetic pathways.
Je
Byoung Il
BI
Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center, Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea.
Piao
Hai Long
HL
Park
Soon Ju
SJ
Park
Sung Han
SH
Kim
Chul Min
CM
Xuan
Yuan Hu
YH
Park
Su Hyun
SH
Huang
Jin
J
Do Choi
Yang
Y
An
Gynheung
G
Wong
Hann Ling
HL
Fujioka
Shozo
S
Kim
Min-Chul
MC
Shimamoto
Ko
K
Han
Chang-deok
CD
D000595:Amino Acid Sequence; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000096:biosynthesis*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D015398:Signal Transduction; D013260:Steroids, Heterocyclic / Q000378:metabolism*; D014170:Transformation, Genetic
D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; D013260:Steroids, Heterocyclic; C519615:BRI1 protein, Oryza sativa; D017346:Protein Serine-Threonine Kinases