Engrailed-ZmOCL1 fusions cause a transient reduction of kernel size in maize.
ZmOCL1 is the founding member of the ZmOCL (Outer Cell Layer) family encoding putative transcription factors of the HD-ZIP IV class. It is expressed in the L1 cell layer of the embryo and several other tissues of maize. After determination of the intron/exon structure a mutator insertion was isolated in the upstream region. No notable phenotypes and wildtype levels of ZmOCL1 transcript were observed in homozygous mutant plants. In contrast transgenic plants carrying a fusion of the repressor domain of the Drosophila Engrailed gene with the DNA binding and dimerisation domains of ZmOCL1 showed a transient reduction of embryo, endosperm and kernel size that was most obvious around 15 DAP. An inverse relationship was observed between the degree of size reduction and the expression level of the transcript. In reciprocal crosses the size reduction was only observed when the transgenic plants were used as females and no expression of male transmitted transgenes was detected. Smaller kernels resembled younger kernels of wild-type siblings indicating that interference with ZmOCL1 function leads to an overall slow-down of early kernel development. Based on marker gene analysis ZmOCL1 may act via a modification of gibberellin levels. Phylogenetic analyses based on the intron/exon structure and sequence similarities of ZmOCL1 and other HD-ZIP IV proteins from maize, rice and Arabidopsis helped to identify orthologues and suggested an evolution in the function of individual genes after the divergence of monocots and dicots.
Khaled
Abdel-Sabour
AS
RDP, UMR879 INRA-CNRS-ENSL-UCBL, IFR128 BioSciences Lyon-Gerland, ENS-Lyon 46 Allée d'Italie, F-69364, Lyon Cedex 07, France.
Vernoud
Vanessa
V
Ingram
Gwyneth C
GC
Perez
Pascual
P
Sarda
Xavier
X
Rogowsky
Peter M
PM
D001665:Binding Sites / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D005091:Exons; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007438:Introns; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics* / Q000254:growth & development; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development
D018744:DNA, Plant; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D008565:Membrane Proteins; C120341:OCL1 protein, Zea mays; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors