A new study led by scientists at the University of California, Davis (UC Davis), and USDA's Agricultural Research Service (ARS) has sequenced the genomes of the English walnut and its wild North American relative using long-read DNA sequencing and optical genome mapping. The genome sequences are the highest quality ever assembled of any woody perennial.

According to Dan Kluepfel, a USDA-ARS scientist and principal investigator of the walnut-rootstock development project, they chose to cross the widely used English walnut with the wild Texas black walnut because of its native resistance to several soil-borne diseases and root nematodes, which are serious pests of walnut in California.

The scientists produced complete genome sequences of the two walnut species in the time normally required to produce the sequence of one genome. These genome sequences will now help researchers identify genetic markers that can be used to develop new varieties with improved pathogen and pest resistance.

For more details, read the news release from UC Davis Department of Plant Sciences.