Establishment of cereal endosperm expression domains: identification and properties of a maize transfer cell-specific transcription factor, ZmMRP-1.
In maize, cells at the base of the endosperm are transformed into transfer cells that facilitate nutrient uptake by the developing seed. ZmMRP-1 is the first transfer cell-specific transcriptional activator to be identified. The protein it encodes contains nuclear localization signals and a MYB-related DNA binding domain. A single gene copy is present in maize, mapping to a locus on chromosome 8. ZmMRP-1 is first expressed soon after fertilization, when the endosperm is still a multinuclear coenocyte. The transcript accumulates in the basal nucleocytoplasmic domain that gives rise to transfer cells after cellularization. The transcript can be detected throughout transfer cell development, but it is not found in mature cells. ZmMRP-1 strongly transactivates the promoters of two unrelated transfer cell-specific genes. The properties of ZmMRP-1 are consistent with it being a determinant of transfer cell-specific expression. Possible roles for ZmMRP-1 in the regulation of endosperm and transfer cell differentiation are discussed.
Gómez
Elisa
E
Departamento Biología Celular y Genética, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid, Spain.
Royo
Joaquín
J
Guo
Yan
Y
Thompson
Richard
R
Hueros
Gregorio
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D020598:Proto-Oncogene Proteins c-myb; D012639:Seeds / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D003313:Zea mays / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D020598:Proto-Oncogene Proteins c-myb; D014157:Transcription Factors