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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #429166
Research Project: Improved Plant Genetic Resources and Methods to ensure Resilient and Productive Rangelands, Pastures, and Turf Landscapes

Location: Forage and Range Research

Title: A haplotype-resolved genome assembly of hexaploid Kentucky-31 tall fescue (Lolium arundinaceum)

Author
item Bushman, Bradley
item Robbins, Matthew
item Behling, William
item Waldron, Blair

Submitted to: G3: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2026
Publication Date: 1/29/2026
Citation: Bushman, B.S., Robbins, M.D., Behling, W.L., Waldron, B.L. 2026. A haplotype-resolved genome assembly of hexaploid Kentucky-31 tall fescue (Lolium arundinaceum). G3: Genes, Genomes, Genetics. 16(4). Article jkag018. https://doi.org/10.1093/g3journal/jkag018.
DOI: https://doi.org/10.1093/g3journal/jkag018

Interpretive Summary: These results show a genome assembly and gene list for hexaploid tall fescue, one of the most important cool-season forage and turf grasses worldwide. The genome was split into the two haplotypes, and each was approximately 7.1Gb in size. We were able to separate the constituent sub-genomes, and found extensive transposable element sequence throughout them. Using this resources as a reference, 15 random sources of the 'Kentucky-31' variety were genotyped with about 3,400 molecular markers. With a hypothesis that all were related and similar genetically, four did not meet that expectation. Three were broad based while a single entry was genetically different than all others.

Technical Abstract: Hexaploid tall fescue is a widely adapted forage and turf grass with three synonyms in botanical nomenclature. It is one of the most drought tolerant cool-season forage and turf species, and can host Neotyphodium endophytes that can further affect physiological traits. The cultivated variety ‘Kentucky-31’ (K31) was one of the original tall fescue varieties yet still has a large presence in the current market. We generated a haplotype-aware assembly of K31 tall fescue along with its chloroplast genome; with structural and functional gene annotation. Each haplotype assembly was approximately 7.1Gb. The three sub-genomes within each haplotype assembly were discernable and syntenic, with the F. pratensis (P) sub-genome intermediate in size between the two sub-genomes from F. glaucescens (G1 and G2). Interspersed repeat levels were high in the assemblies, with long terminal repeats (LTRs) alone comprising over 50% of the genome space. With an interest in testing for K31 as a variety, 15 seed sources of K31 were obtained from forage and turf industry sources and their genetic relationship tested with pairwise PhiST statistics from over 3,400 SNP markers that mapped across the genome. All but four seed sources coalesced into a group that differed from turf-type cultivated variety checks; three were broad-based and did not differ from any other entry; and K31-4 was genetically differentiated from all other K31 sources. These results provide a chromosome-scale and haplotype-aware tall fescue genome assembly for mapping and functional genomic studies.