The hybridization of genetically distinct groups is an important, natural occurrence in many plants that can generate new species and transfer beneficial traits from one group to another. Genetic information, such as which and how many genes affect hybridization, is lacking for most plants, including many ecologically and economically important species. This research will use state-of-the-art DNA sequencing methods to examine the natural hybridization of two ecotypes (genetically distinct varieties adapted to different habitats) of switchgrass, a perennial tallgrass native to North America. These DNA sequencing methods generate hundreds of times more data than previously possible, thus enabling analyses across the entire genome of switchgrass rather than just a handful of genes. The data will be used to identify hybrid populations, analyze patterns of migration, and identify regions in the switchgrass genome that are being transferred between ecotypes or that decrease the success of hybrids. Switchgrass is an emerging bioenergy crop and one of the most widely used species for land conservation. The patterns of genetic variation and hybridization identified in this project will have direct implications on selecting appropriate varieties of switchgrass for bioenergy production and conservation needs. Additionally, the characterized hybrid populations will be valuable resources for future work identifying genes that affect economically important bioenergy traits. Beyond the bioenergy and conservation implications, this proposal will act as a template for implementing new genotyping methods in other ecologically and/or economically important species that, like switchgrass, do not have the research resources of traditional model organisms.
The goal of this project was to use genome-wide data to characterize patterns of hybridization between two major varieties of switchgrass that are adapted to different environments. Genome-wide patterns of hybridization provide information about genes or regions of the genome that may act as barriers to mating between closely related species or sub-species. Alternatively, the patterns can also identify instances in which beneficial genes have been transferred from one species to another, conferring an advantage to both species. In switchgrass, a perennial grass native to North America, there are two major varieties that are adapted to different habitats. Across the majority of the range, the switchgrass varieties are genetically distinct despite often being in very close proximity. However, in certain areas, there is evidence of hybridization between them. By analyzing genome-wide patterns of hybridization, we hoped to identify genes that may prevent or promote intermating between the major switchgrass varieties to better understand why the varieties remain distinct rather than become a single, homogenous variety. Switchgrass is an emerging bioenergy feedstock and an important component of habitat restorations, and better understanding the genetic basis of hybridization between switchgrass varieties is important for both of these uses. Unfortunately, during the period of this grant, several events, particularly the departure of Co-PI Grabowski's research advisors for other research institutions, prevented the accomplishment of the goals of the grant. As such, the grant has been returned in its entirety.
