YABBY Transcription Factor Family
The establishment of abaxial-adaxial polarity in lateral organs involves factors
intrinsic to the primordia and interactions with the apical meristem from which they
are derived. Recently, a small plant-specific family of genes, the YABBY gene family,
has been proposed to specify abaxial cell fate. Each asymmetric above-ground lateral
organ expresses at least one member of the family in a polar manner, and loss- and
gain-of-function studies indicate that they are sufficient to specify abaxial cell fate
and that they act in both distinct and redundant manners.
Members of the YABBY gene family are characterized by two conserved domains, a C2C2
zinc finger-like domain towards the amino terminus and a helix-loop-helix, which we
have called the YABBY domain, with sequence similarity to the first two helices of the
HMG box towards the carboxyl end of the protein.In addition to the conserved YABBY and
zinc finger domains, YAB1, YAB2, YAB3 and YAB5 display some sequence similarity on the
carboxyl side of the YABBY domain. The region between the YABBY and zinc finger domains
is variable amongst family members.
The presence of these domains suggests these proteins function as transcription
factors. Database searches suggest that this family may be plant-specific, as genes
with a similar arrangement of zinc finger and YABBY domains do not occur in either
Caenorhabditis elegans or Saccharomyces cerevisiae.
The YABBY gene are expressed in a polar manner in all lateral organs produced by apical
and flower meristems. Their transcripts are detectable only in the abaxial domains of
lateral organs when their primordia emerge and begin to differentiate. Loss of polar
expression of these genes results in loss of polar differentiation of cell types in
lateral organs, and gain-of-function alleles result in abaxialization of lateral
organs. The expression of these genes is precisely correlated with abaxial cell fate in
mutants in which abaxial cell fates are found ectopically, reduced or eliminated. We
propose that members of this gene family act redundantly to specify abaxial identity in
lateral organs produced by the apical and flower meristems in Arabidopsis.
28 C2C2-YABBY predicted putative peptide ,
CDS , and cDNA sequences;
blast HSP output, multiple sequence alignment,
and phylogeny tree in
Soy - TFKB.
21 C2C2-YABBY protein
and DNA sequences
with
annotations for soybean in PlantTFDB. Most are partial sequences.
Last updated by Dr. Jeff Chen on
June 5, 2009.
