Arabidopsis KANADI1 acts as a transcriptional repressor by interacting with a specific cis-element and regulates auxin biosynthesis, transport, and signaling in opposition to HD-ZIPIII factors.
The formation of leaves and other lateral organs in plants depends on the proper specification of adaxial-abaxial (upper-lower) polarity. KANADI1 (KAN1), a member of the GARP family of transcription factors, is a key regulator of abaxial identity, leaf growth, and meristem formation in Arabidopsis thaliana. Here, we demonstrate that the Myb-like domain in KAN1 binds the 6-bp motif GNATA(A/T) and that this motif alone is sufficient to squelch transcription of a linked reporter in vivo. In addition, we report that KAN1 acts as a transcriptional repressor. Among its targets are genes involved in auxin biosynthesis, auxin transport, and auxin response. Furthermore, we find that the adaxializing HD-ZIPIII transcription factor REVOLUTA has opposing effects on multiple components of the auxin pathway. We hypothesize that HD-ZIPIII and KANADI transcription factors pattern auxin accumulation and responsiveness in the embryo. Specifically, we propose the opposing actions of KANADI and HD-ZIPIII factors on cotyledon formation (KANADI represses and HD-ZIPIII promotes cotyledon formation) occur through their opposing actions on genes acting at multiple steps in the auxin pathway.
Department of Plant Biology and Pathology, Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854.
Tengbo
T
Huang
Yaël
Y
Harrar
Changfa
C
Lin
Brenda
B
Reinhart
Nicole R
NR
Newell
Franklin
F
Talavera-Rauh
Samuel A
SA
Hokin
M Kathryn
MK
Barton
Randall A
RA
Kerstetter
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D018398:Homeodomain Proteins / Q000378:metabolism / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors
D029681:Arabidopsis Proteins; C493946:HD-Zip protein, Arabidopsis; D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; C430846:KANADI protein, Arabidopsis; D012097:Repressor Proteins; D014157:Transcription Factors