CAREER: Genetic and epigenetic regulation of meiotic recombination in maize

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Plant breeding relies on meiotic recombination to combine favorable alleles to develop crops with high yield and other improved traits. Meiotic recombination is a process that determines how parental chromosomes pair up and generate crossovers during sexual reproduction in order to reciprocally exchange genetic material. This makes one individual different from another due to the new and unique combination of alleles. However, breeders rarely know which sex direction of artificial pollination to choose in order to obtain the alleles they need. In order to help breeders determine the direction of pollination that will most enhance their breeding, this project will compare the frequency of meiotic recombination between male and female in corn to understand whether and how meiotic recombination differs between the sexes. The data generated in this project will be used to develop two bioinformatics courses for undergraduate and graduate students who are interested in big data science and advanced plant science. To broaden project impact, a 5-day “Bioinformatics in Plant Science” summer workshop with an emphasis on programming skills and cutting edge technologies will be held annually to train graduate, undergraduate, and high school students. Additionally, high school science teachers will be involved in this project to help them develop science projects for high school curriculum. Recombination has been widely recognized for its role in promoting genetic diversity and largely impacts the efficiency of plant breeding. While enormous progress has been made to decipher the molecular mechanisms of meiotic recombination, how genetic and epigenetic factors are involved in this complicated process, and whether and how recombination differs between male and female meioses in maize are still poorly understood. This project seeks to investigate the meiotic recombination during male and female meioses by using the hybrids of parents of the maize nested association mapping (NAM) population with the reference line B73. These NAM lines were selected to compare male and female meioses because they maximize genetic diversity of the entire maize population. We will first identify the lines that show largest differences with respect to recombination frequency between sexes (Aim 1) and will generate high resolution recombination maps of these lines to compare crossovers between sexes at global and local scales (Aim 2). To determine the causes of such differences between sexes, we aim to elucidate genetic and epigenetic factors important for regulation and control of meiotic recombination (Aim 3). In addition to using the NAM hybrids, a mutant in a RNA directed DNA methylation pathway will be used to particularly dissect the roles of epigenetic modifications in meiotic recombination (Aim 3). This project includes an integrated education portion to broaden the impacts that will be beneficial to graduate, undergraduate, and high school students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.