To understand allele-specific regulation of gene expression, the maize pericarp color1 (p1) gene and its red pigmentation phenotype have been used as a genetic marker. Previous studies demonstrated that allelic variation at the p1 locus is a function of its gene structure, organization, and epigenetic regulatory mechanisms. Maize plants carrying the P1-wr (white pericarp & red cob glumes) allele produce ears with colorless kernel pericarp and red cob glumes and this phenotype is stable over generations. However, in the presence of Ufo1 (Unstable factor for orange1), the P1-wr allele confers variably enhanced pigmentation phenotypes in several tissues that include pericarp, cob glume, leaf sheath and husk. Ufo1 is a dominant modifier of p1 expression and it is unlinked from p1. Expression studies demonstrated that Ufo1-induced gain of p1 regulated pigmentation is associated with increased steady state levels of p1 RNA and decreased DNA methylation of P1-wr. To identify the nature of ufo1 gene and the mechanism of its action, further molecular and genetic characterization will be performed during this project. The first set of experiments will fine map the position of Ufo1 on chromosome 10S and these results will identify candidates for the ufo1 gene. The second objective will compare how the DNA methylation of single copy and multicopy alleles of p1 are affected by Ufo1. The third objective will examine the role of ufo1 in the maintenance of paramutation in two maize loci. This research will advance the current understanding of how overlapping epigenetic pathways uniquely regulate allele-specific patterns. The significance of this project is its elucidation of a class of modifiers of gene expression that can regulate or disrupt a well-programmed expression profile via transient changes in the DNA methylation or chromatin of specific target loci. Eukaryotic gene regulatory mechanisms can restrict the expression of a gene to a specific tissue or a cell type. Most such patterns of expression are stably maintained due to the faithful transmission of alleles. Nevertheless, there are mechanisms that allow diversification of form and function. One such mechanism is epigenetic regulation operating through alterations in DNA methylation or in the packaging of DNA into chromatin. In this project the investigator will use the maize pigmentation regulatory gene p1 as a model system through which to understand the molecular basis of tissue specificity imposed in the form of alleles. to Understanding the basis of this unique type of allelic variability that exists in the form of natural and stable alleles is of great interest to biologists and plant breeders working to develop improved crops. This project will provide training for graduate and undergraduate students in the field of plant epigenetics. Furthermore, each summer the PI hosts two interns from the Pennsylvania Governor's School for Agricultural Sciences for independent study projects in maize genetics and molecular biology. The PI also participates in several mentoring programs for underrepresented undergraduates and collaborates with Dr. Sarwan Dhir of Fort Valley State University, a minority-serving institution in Georgia, in an NSF-funded REU program providing education and training to minorities and women in the field of plant biology, genetics and biotechnology.
|Effective start/end date||8/15/06 → 12/31/11|
- National Science Foundation: $539,239.00