A population genomics approach to accelerating the domestication of the energy grass Miscanthus.

Because of their high productivity, C4 grasses from the tropical genus Miscanthus are believed to have great potential as a bioenergy crop. However, they are essentially undomesticated and their outcrossing mating systems and perennial life cycles are serious challenges for breeding programs. One approach to accelerating the domestication of Miscanthus is to harness the tremendous genetic variation that is present within this genus using phenotypic data from extensive field trials, high-density genotyping and sequencing technologies, and rapidly developing statistical methods of relating phenotype to genotype. We used molecular and phenotypic data to depict patterns of population genetic structure among Miscanthus genotypes grown in a field trial near Aberystwyth (UK) and delineate an experimental population for genome-wide association studies (GWAS) and genomic selection (GS). Despite the relatively small scale of our pilot study (142 genotypes and ~50,000 single-nucleotide polymorphisms detected through genotyping by sequencing), preliminary results are encouraging, with predictive abilities of GS (i.e., correlation of observed and predicted genetic values) as high as 0.7 for phenological traits and 0.6 for traits related to biomass productivity and cell wall composition. We therefore discuss the prospects of incorporating GS into Miscanthus breeding programs, focusing on the key factors that will likely determine the feasibility of this approach.