Data from: Molecular and morphological diversity of on-farm hazelnut (Corylus avellana L.) landraces from southern Europe and their role in the origin and diffusion of cultivated germplasm

Hazelnut (Corylus avellana L.) is a traditional nut crop in southern Europe. Germplasm exploration conducted on-farm in five countries (Portugal, Spain, Italy, Slovenia, and Greece) identified 77 landraces. The present work describes phenotypic variation in nut and husk traits and investigates genetic relationships using 10 simple sequence repeat (SSR) markers among these landraces, 57 well-known references cultivars, and 19 wild accessions. Among the 77 landraces, 42 had unique fingerprints while 35 showed a SSR profile identical to a known cultivar. Among the 42 unique landraces, morphological observations revealed high phenotypic diversity and some had characteristics appreciated by the market such as nut round and calibre Analysis of genetic relationships and population structure allowed investigation of the origin and spread of the cultivated germplasm in southern Europe. Our results indicate the existence of three primary centres of diversity in the Mediterranean basin: northwestern Spain (Tarragona) and southern Italy (Campania) in the West and Black Sea (Turkey) in the East. Moreover, the data suggests the existence of secondary gene pools in the Iberian (Asturias) and Italian (Liguria and Latium) Peninsulas, where local varieties were recently domesticated from wild forms and/or from introduced ancient domesticated varieties.

欧洲榛（Corylus avellana L.）是南欧的传统坚果作物。研究团队针对葡萄牙、西班牙、意大利、斯洛文尼亚及希腊五国开展田间种质资源（germplasm）勘探，共筛选得到77份地方品种（landrace）。本研究对上述77份地方品种、57份知名参考栽培品种以及19份野生种质材料的坚果与果苞性状的表型变异进行了系统描述，并利用10个简单序列重复（simple sequence repeat, SSR）标记分析了其遗传关系。在这77份地方品种中，42份拥有独特的分子指纹图谱，剩余35份的SSR分型结果与某一已知栽培品种完全一致。对这42份独特地方品种的形态学观测显示其表型多样性丰富，部分品种具备市场青睐的优良性状，如圆形坚果与标准果径。通过遗传关系与群体结构分析，本研究得以探究南欧栽培榛种质资源的起源与传播路径。研究结果表明，地中海盆地存在三个核心种质多样性中心：西部为西班牙西北部（塔拉戈纳）与意大利南部（坎帕尼亚），东部为黑海沿岸（土耳其）。此外，研究数据显示伊比利亚半岛（阿斯图里亚斯）与意大利半岛（利古里亚及拉齐奥）存在次级基因库，该区域的地方品种近期由野生类群或引入的古老栽培品种驯化而来。