The genus Juglans resides within the order Fagales, which contains several genera of important nut and timber trees including birch, beech, oak, chestnut, butternut, and pecan. Persian walnut (Juglans regia, also known as English walnut) is a valuable agricultural commodity, with annual production valued at over $500 million in California. Genomic resources developed for walnut will improve the knowledge base for all these tree species. The model plants most closely related to walnut outside the Fagales order are the legumes (Medicago sp., Lotus sp., soybean) and poplar. Slightly more distant relatives include grape and Arabidopsis.

The walnut genome includes the following components:

• Construction of a physical map of the walnut genome
• Functional genomics survey of walnut gene expression
• Fine-scale genetic mapping of economically important traits
• Web data portal containing all physical and linkage mapping information and integrating all ESTs into the walnut physical and genetic maps.