Chromosome-level reference genome of a foundational California native legume, Acmispon strigosus

Acmispon is a legume genus that has diversified within the California Floristic Province. Acmispon species live in a variety of habitats, including coastal sage scrub, deserts, grasslands, and woodlands, and form symbiotic associations with nitrogen-fixing bacteria. Here, we report the first chromosome-level assembly of Acmispon strigosus (strigose bird's-foot trefoil or strigose lotus) as part of the California Conservation Genomics Project. Consistent with the reference genome pipelines of the California Conservation Genomics Project, we used Pacific Biosciences HiFi long reads and Hi-C chromatin-proximity sequencing technology to produce a de novo assembled genome. The assembly is 519 Mb in length, with a contig N50 of 22.97 Mb, scaffolded into seven pseudochromosomes. Using the NCBI EGAPx pipeline, we annotated a total of 21,347 genes resulting in a protein Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness score of 91.5%. This is the first genome assembled for Acmispon and among the first genomic resources available for a native California legume. The assembly BUSCO completeness score of 94.8% makes it one of the most complete genomes for the tribe Loteae (Fabaceae). Generating whole-genome sequences will contribute to our general understanding of nitrogen-fixing legume's adaptations to diverse soil and environmental conditions, interactions with nitrogen fixing Bradyrhizobium and Mesorhizobium symbionts, and the degrading effects of pollution-induced nitrogen deposition on the legume-rhizobium symbiosis in California. These data will also help to reconstruct phylogenetic relationships among Acmispon spp., which remain unresolved.