First complete zoysia grass genome assembled, enabling drought-tolerant breeding

Scientists at Texas A&M AgriLife Research have assembled the first near gap-free, haplotype-resolved genome for Zoysia japonica, a warm-season turfgrass widely used across the southern and transitional United States. The study, published in Plant Biotechnology Journal, resolves the species' complex tetraploid structure and identifies a key chromosomal difference within a single genome that had previously hindered genetic analysis.

Zoysia grass carries four sets of chromosomes and reproduces through open pollination, making traditional trait selection slow and labor-intensive. Lead researcher Murukarthick Jayakodi, a plant genomicist at the Texas A&M AgriLife Research and Extension Center at Dallas, said the new assembly allows breeders to pinpoint genes linked to stress tolerance rather than relying on years of field trials.

The team leveraged advances in long-read sequencing and genome assembly technologies to overcome the polyploid complexity that had left zoysia genetics a "black box." Collaborators included Ambika Chandra, leader of the Turfgrass Breeding and Urban Landscapes Program, and researchers Preethi Purushotham and Sae Hyun Lee.

With the genome in hand, the researchers plan to develop molecular markers for drought, heat, and other abiotic stress tolerances. Jayakodi said the goal is to build predictive models for turf performance and extend the approach to other zoysia species, enabling earlier selection of varieties that stay green under low-water conditions.

The turfgrass industry has long sought cultivars that maintain quality with reduced irrigation. Chandra noted that the ability to predict trait expression at early breeding stages represents the next major advance, and the new genomic resource provides the foundation for that work.