In France, walnut crop is the second largest fruit crop after apple, with 36,000 tons of in-shell walnuts produced in 2016, making France the 9 th producer in the world with almost 20,000 ha devoted. The INRAE's walnut germplasm collection includes 253 accessions from worldwide thanks to the prospecting work of Eric Germain from 1977 to 2007, the former head of breeding program at INRAE of Bordeaux. Among them, 217 are Juglans regia accessions including 194 cultivars and 23 intraspecific hybrids, coming from the major growing areas such as North-America, Europe and Asia. The germplasm collection includes also 36 Juglans accessions of 14 related species from the two sections