Accessing Natural Variation in Brachypodium distachyon: Development of the ABR6 x Bd21 RIL Population

A critical requirement for investigating natural variation is the identification of diverse germplasm and the development of mapping populations that capture the diversity of a species. The Brachypodium distachyon community has focused on sampling diverse germplasm from the natural range of the species and developing RIL populations that span this diversity. Here, we describe the development of the ABR6 x Bd21 recombinant inbred line (RIL) population, which has recently been advanced to the F₉ stage. The population segregates for a range of morphological characteristics including above-ground biomass, plant height, leaf length and width, grain traits (width, length, height, and thousand grain weight), shattering, trichrome density, reaction to pathogenic microbes, and flowering time. In parallel, genetic and genomic resources have been developed including high-throughput sequencing of ABR6, ABR6 BAC library, and a high-density genetic map. Map-based cloning is underway for several genes underlying these diverse traits and current progress will be discussed.