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1.
Plant J ; 18(1): 111-9, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10341448

ABSTRACT

Mutations at the SCARECROW (SCR) locus in Arabidopsis thaliana result in defective radial patterning in the root and shoot. The SCR gene product contains sequences which suggest that it is a transcription factor. A number of Arabidopsis Expressed Sequence Tags (ESTs) have been identified that encode gene products bearing remarkable similarity to SCR throughout their carboxyl-termini, indicating that SCR is the prototype of a novel gene family. These ESTs have been designated SCARECROW-LIKE (SCL). The gene products of the GIBBERELLIN-INSENSITIVE (GAI) and the REPRESSOR of ga1-3 (RGA) loci show high structural and sequence similarity to SCR and the SCLs. Sequence analysis of the products of the GRAS (GAI, RGA, SCR) gene family indicates that they share a variable amino-terminus and a highly conserved carboxyl-terminus that contains five recognizable motifs. The SCLs have distinct patterns of expression, but all of those analyzed show expression in the root. One of them, SCL3, has a tissue-specific pattern of expression in the root similar to SCR. The importance of the GRAS gene family in plant biology has been established by the functional analyses of SCR, GAI and RGA.


Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/genetics , Co-Repressor Proteins/genetics , Genes, Plant , Multigene Family , Amino Acid Sequence , Conserved Sequence , Evolution, Molecular , Gene Expression , In Situ Hybridization , Molecular Sequence Data , Mutation , Sequence Homology, Amino Acid
2.
Gene ; 177(1-2): 203-8, 1996 Oct 24.
Article in English | MEDLINE | ID: mdl-8921868

ABSTRACT

The maize proteins Opaque-2 (O2) and OHP1 are members of the bZIP class of transcriptional regulatory proteins. The genomic organizations of the O2 and OHP1 genes are conserved in terms of the number and placement of introns which suggests a common evolutionary origin. The organization of O2 and OHP1 contrasts with the maize bZIP protein gene OBF1, which lacks introns, suggesting that there exist at least two evolutionary paths for bZIP genes in maize. The OHP1 gene is located on chromosome 1L and a duplicate gene, OHP2, is located on 5S. Interestingly, the OHP1 gene, but not OHP2, has been amplified within recent history. Two out of ten maize inbreds analyzed contain multiple linked copies of OHP1, and in one of these lines at least two copies of the OHP1 genes are expressed. This variation in copy number among inbreds may prove useful in understanding the role of OHP1 in maize growth and development and yield insights into the evolution of this group of bZIP DNA binding proteins.


Subject(s)
Genes, Plant , Genetic Variation , Leucine Zippers/genetics , Nuclear Proteins , Transcription Factors/genetics , Zea mays/genetics , Amino Acid Sequence , DNA, Complementary/isolation & purification , DNA-Binding Proteins/genetics , Evolution, Molecular , Exons , Gene Dosage , Inbreeding , Introns , Molecular Sequence Data , Multigene Family , Plant Proteins/genetics , Sequence Homology, Amino Acid
3.
Cell ; 86(3): 423-33, 1996 Aug 09.
Article in English | MEDLINE | ID: mdl-8756724

ABSTRACT

In the Arabidopsis root meristem, initial cells undergo asymmetric divisions to generate the cell lineages of the root. The scarecrow mutation results in roots that are missing one cell layer owing to the disruption of an asymmetric division that normally generates cortex and endodermis. Tissue-specific markers indicate that a heterogeneous cell type is formed in the mutant. The deduced amino acid sequence of SCARECROW (SCR) suggests that it is a member of a novel family of putative transcription factors. SCR is expressed in the cortex/endodermal initial cells and in the endodermal cell lineage. Tissue-specific expression is regulated at the transcriptional level. These results indicate a key role for SCR in regulating the radial organization of the root.


Subject(s)
Arabidopsis Proteins , Arabidopsis/genetics , Plant Proteins/physiology , Plant Roots/cytology , Amino Acid Sequence , Arabidopsis/cytology , Base Sequence , Cell Division , Cloning, Molecular , DNA, Plant/analysis , Genes, Regulator/genetics , Molecular Sequence Data , Plant Proteins/genetics , Transcription, Genetic
4.
Plant Cell ; 5(2): 227-36, 1993 Feb.
Article in English | MEDLINE | ID: mdl-8453304

ABSTRACT

OPAQUE2 (O2) is a regulatory gene that predominantly affects the expression of the 22-kD class of zein storage protein genes at the level of transcription. The O2 gene encodes a polypeptide belonging to the basic domain/leucine zipper (bZIP) class of transcriptional regulatory proteins. Our prior analyses have demonstrated that the O2 protein binds 22-kD zein gene promoters as a homodimer in vitro and have also suggested that O2 may bind as a heterodimer in vivo. To identify cDNAs encoding other bZIP motifs that might interact with O2, a portion encoding the bZIP motif from an O2 cDNA was used to screen an endosperm cDNA library. Sequence analysis of one isolated recombinant phage indicated the presence of a bZIP motif similar to O2. The protein product of this partial cDNA, designated OHP1, can bind the O2 target site both as a homodimer and in a heterodimeric complex with O2. Whole genome DNA gel blot analysis of maize recombinant inbreds revealed two strongly hybridizing restriction fragments, neither of which mapped close to any locus known to affect zein expression. RNA gel blot analysis revealed an approximately 1.7-kb transcript that is expressed in all organs examined except the female flower and is also expressed in endosperms homozygous for o2 and other mutations that affect zein expression (opaque7, floury2, and Defective endosperm b-30). Based on these results and previously reported data, we propose models to accommodate OHP1 in the regulation of zein gene expression by O2.


Subject(s)
DNA-Binding Proteins/metabolism , Leucine Zippers/physiology , Plant Proteins , Plants/metabolism , Transcription Factors/metabolism , Zein/metabolism , Amino Acid Sequence , Base Sequence , DNA/genetics , DNA-Binding Proteins/genetics , Gene Expression Regulation , Genes, Regulator , Leucine Zippers/genetics , Molecular Sequence Data , Mutation , Plants/genetics , Transcription Factors/genetics , Zein/genetics
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