24Setaria viridis (green foxtail) is an important model system for improving cereal crops 25 due to its diploid genome, ease of cultivation, and use of C4 photosynthesis. The S. 26 viridis cultivar ME034V is exceptionally transformable, but the lack of a sequenced 27 genome for this cultivar has limited its utility. We present a 397 Mb highly contiguous de 28 novo assembly of ME034V using ultra-long nanopore sequencing technology (read 29 N50=41kb). We estimate that this genome is largely complete based on our updated k-30 mer based genome size estimate of 401 Mb for S. viridis. Genome annotation identified 31 37,908 protein-coding genes and >300k repetitive elements comprising 46% of the 32 genome. We compared the ME034V assembly with two other previously sequenced 33Setaria genomes as well as to a diversity panel of 235 S. viridis cultivars. We found the 34 genome assemblies to be largely syntenic, but numerous unique polymorphic structural 35 variants were discovered. Several ME034V deletions may be associated with recent 36 retrotransposition of copia and gypsy LTR repeat families, as evidenced by their low 37 genotype frequencies in the sampled population. Lastly, we performed a phylogenomic 38 analysis to identify gene families that have expanded in Setaria, including those 39 involved in specialized metabolism and plant defense response. The high continuity of 40 the ME034V genome assembly validates the utility of ultra-long DNA sequencing to 41 improve genetic resources for emerging model organisms. Structural variation present 42 in Setaria illustrates the importance of obtaining the proper genome reference for 43 genetic experiments. Thus, we anticipate that the ME034V genome will be of significant 44 utility for the Setaria research community. 45 47 Grasses of the genus Setaria represent diverse species, with phenotypes ranging from 48 the domesticated food crop foxtail millet, S. italica, to its weedy ancestral progenitor, 49 green foxtail, S. viridis (Li and Brutnell 2011). Simple growth requirements, small 50 stature, and short lifecycle make Setaria a tractable monocot model system for studying 51 C4 photosynthesis (Brutnell et al. 2010; Li and Brutnell 2011; Van Eck and Swartwood 52 2015). Furthermore, close phylogenetic relationships with agriculturally important crops 53 such as maize and sorghum promise to inform genetic and cell biology knowledge of 54 other food crops of global importance. Current genome resources for Setaria include a 55 reference genome for S. italica (Bennetzen et al. 2012; Zhang et al. 2012) based on the 56 cultivar Yugu1, a variety of foxtail millet widely grown as a food crop in China. 57 Additionally, a de novo assembly of S. viridis cultivar A10.1 (hereafter referred to as 58 A10) was recently made available alongside low coverage resequencing of more than 59 600 Setaria ecotypes (Huang et al. 2019). 60 61 Efficient genetic modification is a primary requirement for development of any model 62 organism. Approaches for Setaria protoplasting, particle bombardment, and 63...