Heterosis (or hybrid vigor) is the phenomenon where the progeny of diverse inbred parents within a species have superior biomass, stature and/or fertility compared to either of the inbred parental lines. Although heterosis is commonly exploited in crop production, the molecular basis is largely unknown. This proposal will address whether small RNAs and epigenetic modifications (such as histone modifications and DNA methylation) are involved in regulation of heterosis in maize. This project will employ next-generation sequencing to provide genome-wide profiling of messenger RNA and small RNA transcriptomes and selected epigenetic modifications in two inbred lines and their reciprocal hybrid offspring. A systematic analysis of these data will provide genome-wide maps of DNA methylation, histone modification patterns, sequence polymorphisms, small RNA abundance, and gene expression levels in the maize inbred lines and their reciprocal hybrids. This in-depth analysis of a selected model pair of maize lines will aid in achieving the long-term goal of understanding the molecular mechanisms of heterosis in maize.
Understanding the molecular events underlying heterosis has the potential to improve crop and livestock breeding programs. In addition, because heterosis is potentially a driving evolutionary force, elucidating its molecular basis will contribute to our understanding of the evolution of species. This project will provide training to young researchers at the postdoctoral, graduate, and undergraduate levels. In addition, the project will support an outreach program that couples undergraduate summer research projects with undergraduate classes and projects during the academic year. This project will be integrated into undergraduate bioinformatics and molecular biology curricula through class assignments and project-based lessons. Project personnel will also participate in various outreach events targeting younger students. A website (http://plantgenomics.biology.yale.edu) will be developed to provide public access to the data and provide a summary of the project. All datasets will be deposited at the NIH GEO repository (www.ncbi.nlm.nih.gov/geo) and the Plant Gene Expression database (PLEXdb) at http://plexdb.org.
