title: Hierarchical patterns of transgene expression indicate involvement of developmental mechanisms in the regulation of the maize P1-rr promoter.
abstract: The maize P1-rr gene encodes a Myb-homologous transcription factor that regulates the synthesis of red flavonoid pigments. Maize plants transformed with segments of the P1-rr promoter driving a GUS reporter gene exhibit significant variation in transgene expression, both between independent transformation events and among sibling plants derived from a single event. Interestingly, variability in spatial expression is not random; rather, transgene activity occurs predominantly in five patterns that fit a hierarchy: expression is most common in kernel pericarp, with sequential addition of expression in cob glumes, husk, silk, and tassel. The hierarchical expression pattern of P-rr::GUS transgenes suggests a possible model for developmental regulation of the P1-rr gene. Our results demonstrate that variability in transgene expression, a common occurrence in transgenic plant studies, can be informative if adequately analyzed to uncover underlying patterns of gene expression.
authors.affiliation: Department of Zoology and Genetics, Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Cocciolone
authors.forename: L V
authors.initials: LV
authors.lastname: Sidorenko
authors.forename: S
authors.initials: S
authors.lastname: Chopra
authors.forename: P M
authors.initials: PM
authors.lastname: Dixon
authors.forename: T
authors.initials: T
authors.lastname: Peterson
mesh_terms: D004742:Enhancer Elements, Genetic; D005419:Flavonoids / Q000096:biosynthesis; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000235:genetics*
chemical_list: D005419:Flavonoids; D014157:Transcription Factors; D005966:Glucuronidase