Genome-Wide Divergence Between Upland and Lowland Ecotypes of Panicum hallii, a Close Relative of Switchgrass

Local adaptation to abiotic stress is responsible for much of the observed genetic diversity within wild plant species and landraces of crops. For example, selection on drought adaptation strategies can contribute to the formation of upland (drought tolerant) and lowland (mesic) ecotypes. Such ecotypes have have diverged at many thousands of loci and most measurable phenotypes. Interestingly, when crossed, upland-lowland hybrids often exhibit heterosis, indicating that deleterious mutations have accumulated alongside adaptive sequence variants. Here, we characterize sequence and gene expression divergence and analyze sequence variants that may underlie whole-plant heterosis between upland and lowland ecotypes of Panicum hallii, a diploid genomic model of Switchgrass.