This action funds an NSF National Plant Genome Initiative Postdoctoral Research Fellowship in Biology for FY 2018. The fellowship supports a research and training plan in a host laboratory for the Fellow who also presents a plan to broaden participation in biology. The title of the research and training plan for this fellowship to Manisha Munasinghe is "Genetic Determinants of Hybrid Decay in Backcross Populations of Teosinte with Maize". The host institution for the fellowship is the University of Minnesota and the sponsoring scientists are Drs. Yaniv Brandvain and Nathan Springer.
Plant breeders seek to take advantage of useful genetic variants present in wild relatives of crop species. Genetic incompatibilities between species can work against this goal, which makes understanding how they emerge and persist in populations highly relevant. A unique incompatibility between the crop species maize and its wild relative the Mexican teosinte is thought to be triggered by the uncontrolled proliferation of repetitive DNA in hybrids. This project is designed to not only identify the specific genetic variants underlying this incompatibility but also to use this knowledge to expand evolutionary theory to better understand how these variants become established in populations. Training objectives for the Fellow include plant biology, computational biology, statistical genetics, and analytical modeling. Broader impacts include the development of two teaching modules in genetics and statistics for undergraduate students and providing mentoring and training through participation in the Carpentries (www.carpentries.org) computational training workshops.
There is a longstanding interest in understanding the genomic basis of reproductive isolation as it can both inform how speciation occurs and the evolutionary forces occurring within lineages. The uncoupling of selfish repetitive DNA, such as transposable elements, and the molecular machinery that epigenetically silences their proliferation is a potential cause of hybrid incompatibility that has received comparatively little attention. This project explores an unusual case of hybrid incompatibility between the crop species maize and its wild relative Mexican teosinte thought to be caused by the uncoupling of repetitive DNA from the variants that halt their proliferation. No abnormal phenotype in the F1 hybrids, the persistence of the incompatibility despite recurrent backcrossing to maize, and epigenetic changes in hybrids distinguish this case from others. This project will characterize the genomic basis of this epistatic incompatibility, estimate its frequency in nature, and model its impacts on genome-wide patterns of introgression. Long-read, whole-genome sequencing will allow the fine-scale characterization of changes in repetitive DNA between the parental species and hybrids. Additional teosinte samples will be collected to perform population-level analyses to identify regions under selection, which will likely include repetitive DNA repressor systems. Finally, the consequence of uncoupling repetitive DNA from its repressor system will be modelled to characterize its effect on population divergence. All computer pipelines and codes will be shared publicly so other researchers may adapt these tools to their needs. Raw data/code will be released through public repositories, such as GitHub or NCBI. Processed datasets will be released through CyVerse Data Commons, Dryad, or DRUM (www.lib.umn.edu/datamanagement/drum). All processed data and any files that may be of interest to the broader community will be made publicly available through CyVerse or GitHub and will also be shared with MaizeGDB.
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.
