Investigating Paramutation at the Maize b1 Gene: Molecular Mechanisms of Heritable Epigenetic Gene Regulation

University Of Arizona, Tucson AZ

Investigators

Abstract

Intellectual Merit: How an individual's genes are activated or silenced is an essential question impacting all fields of biology. Gene expression patterns, i.e. which genes are on and which are off in different tissues and during development, are highly reproducible among individuals of each species and those patterns are efficiently reset every generation. One exception to these genetic rules is paramutation in maize. Paramutation leads to certain genes becoming silenced and that silencing is retained when the genes are transmitted to offspring. Depending on which genes are silenced dramatic changes in the plant's growth and development can be observed. Prior work has demonstrated that these heritable changes in gene expression are mediated by RNA, demonstrating RNA is not just a vehicle for DNA's commands; it is able to issue its own commands that alter how genes are expressed in the next generation. This project is to characterize a gene that is required for paramutation, mop3 (mediator of paramutation3). Initial research has demonstrated that mop3 acts at a distinct step in RNA mediated gene silencing relative to other previously characterized genes required for paramutation. Thus, new mechanistic insights should be gained from further study of mop3 as well as from the isolation and characterization of additional genes required for paramutation, another major goal of this project. Understanding mechanisms for heritable changes in gene expression will provide new insights into how plants might mediate adaptive responses to a changing environment. Broader Impacts: The investigators for this project have had a long standing commitment to training and outreach. During the past 12 years, 5 postdoctoral fellows, 8 graduate students, 45 undergraduate students, 10 high school students and 5 high school teachers have participated in the research efforts that generated the data that formed the basis for this project. The current research project will provide training for two undergraduate students each year and a high school teacher and her students. The high school teacher will participate in a summer internship each year that will involve direct participation in the experiments and designing curriculum to engage the high school students during the academic year. The teacher will participate in a broad network with other teachers so that each person's curriculum innovation can be shared and thus, contribute to an increase in the science literacy of a larger number of students.