A moderate genetic diversity, the absence of a significant genetic differentiation between wild and cultivated stands and a highly admixed genetic structure of sweet chestnut with two main clusters were observed in France using two different data sets with 10 and 18 microsatellites. Renewed interest in European chestnut in France is focused on finding locally adapted populations partially resistant to ink disease and identifying local landraces. We genotyped trees to assess (i) the genetic diversity of wild and cultivated chestnut across most of its range in France, (ii) their genetic structure, notably in relation with the sampled regions, and (iii) to a lesser extent the relations between French chestnuts with 10 cultivated chestnuts from the Northwest of Spain that were previously classified in the Iberian or Italian groups. A total of 693 trees in 16 sampling regions in France were genotyped at 24 SSRs and 1401 trees in 17 sampling regions at 13 SSRs. Genetic diversity was moderate in most sampling regions, with redundancy between them. No significant differentiation was found between wild and cultivated chestnut. A genetic structure analysis with no a priori information found a low yet significant structure and identified two clusters at 18 SSRs. One cluster gathers trees from south-east France and Corsica (RPP1), and another cluster gathers trees from all other sampled regions (RPP2). A substructure was detected at 10 SSRs suggesting differentiation within both RPP1 and RPP2. RPP1 was split between south-east France and Corsica. RPP2 was split between northwest France, Aveyron, Pyrenees, and a last cluster gathering individuals from several other regions. The genetic structure within and between our sampling regions is likely the result of natural events (recolonization after the last glaciation) and human activities (migration and exchanges). These advances on our knowledge of chestnut genetic diversity and structure will benefit conservation and help our local partners’ valorization efforts.

中文翻译：

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法国森林和栽培板栗 (Castanea sativa Mill.) 之间具有高度混合的两个主要遗传簇

在法国使用具有 10 个和 18 个微卫星的两个不同数据集观察到中等遗传多样性，野生和栽培林分之间没有显着的遗传差异，以及具有两个主要簇的高度混合的甜板栗遗传结构。法国对欧洲板栗的新兴趣集中在寻找当地适应的对墨病有部分抵抗力的种群，并确定当地的地方品种。我们对树木进行基因分型以评估 (i) 法国大部分地区野生和栽培板栗的遗传多样性，(ii) 它们的遗传结构，特别是与采样区域的关系，以及 (iii) 在较小程度上法国栗子和 10 种来自西班牙西北部的栽培栗子，以前被归类为伊比利亚或意大利组。在法国 16 个采样区域的 693 棵树在 24 个 SSR 和 17 个采样区域的 1401 棵树在 13 个 SSR 进行了基因分型。大多数采样区域的遗传多样性中等，它们之间存在冗余。野生板栗和栽培板栗之间没有发现显着差异。没有先验信息的遗传结构分析发现了一个低但显着的结构，并在 18 个 SSR 处确定了两个簇。一个集群收集来自法国东南部和科西嘉岛 (RPP1) 的树木，另一个集群收集来自所有其他采样区域 (RPP2) 的树木。在 10 个 SSR 处检测到亚结构，表明 RPP1 和 RPP2 均存在分化。RPP1 在法国东南部和科西嘉岛之间分裂。RPP2 分为法国西北部、阿韦龙、比利牛斯和最后一个聚集了来自其他几个地区的个体。我们采样区域内和之间的遗传结构很可能是自然事件（最后一次冰川作用后的重新殖民）和人类活动（迁徙和交流）的结果。我们对板栗遗传多样性和结构的了解取得的这些进展将有利于保护并帮助我们当地合作伙伴的价值评估工作。