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: northweste...榛子（Corylus avellana L.）是南欧的传统坚果栽培作物。研究团队在葡萄牙、西班牙、意大利、斯洛文尼亚与希腊五个国家开展农场内种质资源调查，共鉴定得到77份地方品种。本研究对这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壳性状表型变异进行描述，并利用10个简单序列重复（simple sequence repeat, SSR）标记探究其遗传关系。在77份地方品种中，42份具有独特的分子指纹图谱，剩余35份的SSR分型结果与已知栽培品种完全一致。在这42份独特地方品种中，形态学观测显示其存在较高的表型多样性，部分品种具备市场青睐的优良性状，如圆润的坚果外形与果径。遗传关系与群体结构分析可用于探究南欧栽培种质的起源与传播路径。本研究结果表明，地中海盆地存在三个核心多样性中心：西北...