This folder contains genotyping data for Bromus tectorum accessions collected throughout the PNW small grain production region. Data was obtained using a reduced representation genotype-by-sequencing (GBS) approach to identifying SNP molecular markers. The GBS approach used in relied upon a combination of a regular and a methylation-sensitive restriction enzyme to avoid repetitive regions of a target genome and instead favor lower copy regions to increase the probability of identifying informative genetic markers. A two-enzyme approach originally developed for species lacking a reference genome was utilized, where a rare (Pst1, CTGCA^G) and common (Msp1, C^CGG) restriction enzyme were used in combination. A modified GBS protocol developed by Mascher et al. (2013) for use with semi-conductor sequencing platform was followed according to protocol. The resulting amplicons were sequenced on an Ion Proton™ sequencer using an Ion P1™ Chip (Life Technologies, Carlsbad, CA). The master FASTQ file obtained from the sequencer was parsed by barcode to separate each accession into a separate file. FASTQ file size ranged from 5 to 112 MBs with an average size of 45.6 MBs