The maize unstable factor for orange1 is a dominant epigenetic modifier of a tissue specifically silent allele of pericarp color1.
We have characterized Unstable factor for orange1 (Ufo1), a dominant, allele-specific modifier of expression of the maize pericarp color1 (p1) gene. The p1 gene encodes an Myb-homologous transcriptional activator of genes required for biosynthesis of red phlobaphene pigments. The P1-wr allele specifies colorless kernel pericarp and red cobs, whereas Ufo1 modifies P1-wr expression to confer pigmentation in kernel pericarp, as well as vegetative tissues, which normally do not accumulate significant amounts of phlobaphene pigments. In the presence of Ufo1, P1-wr transcript levels and transcription rate are increased in kernel pericarp. The P1-wr allele contains approximately six p1 gene copies present in a hypermethylated and multicopy tandem array. In P1-wr Ufo1 plants, methylation of P1-wr DNA sequences is reduced, whereas the methylation state of other repetitive genomic sequences was not detectably affected. The phenotypes produced by the interaction of P1-wr and Ufo1 are unstable, exhibiting somatic mosaicism and variable penetrance. Moreover, the changes in P1-wr expression and methylation are not heritable: meiotic segregants that lack Ufo1 revert to the normal P1-wr expression and methylation patterns. These results demonstrate the existence of a class of modifiers of gene expression whose effects are associated with transient changes in DNA methylation of specific loci.
Chopra
Surinder
S
Department of Zoology and Genetics and Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA.
Cocciolone
Suzy M
SM
Bushman
Shaun
S
Sangar
Vineet
V
McMullen
Michael D
MD
Peterson
Thomas
T
D002467:Cell Nucleus / Q000235:genetics; D019175:DNA Methylation; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D005819:Genetic Markers; D010940:Plant Proteins / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics*
D018744:DNA, Plant; D005819:Genetic Markers; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; C480438:Ufo1 protein, maize