Dutch elm disease (DED) is a devastating forest disease. Recently, the deployment of native resistant cultivars has prompted initiatives of elm reintroduction in Europe and North America. It is known that DED resistance varies with the tree genotype and is influenced by climatic factors. However, genotype-by-environment interactions in DED resistance remain largely unexplored. In this work, we examined whether there is genetic variation in DED resistance plasticity and the roles of tree growth, phenology and anatomical traits in plastic responses. We established two experimental plots with 12 Ulmus minor genotypes in two environmentally contrasting locations in Spain: Madrid, under an inland continental climate, and Valencia, under a coastal Mediterranean climate. We monitored growth and phenology detecting high plasticity in both traits. In the inland plot, genotypes were taller and showed a more synchronized phenology than in the coast. A first DED-pathogen inoculation was carried out 45 days after the average flushing date in each location, after which trees exhibited more symptoms inland. A second inoculation was carried out by dividing the coastal plot trees into early and late flushing trees and inoculating each group at 45 days after its average flushing date. Therein, susceptibility rose to a level close to the inland plot. In both inoculations, we detected a significant genotype-by-location interaction in DED resistance. The xylem anatomy revealed high plasticity and a significant genotype-by-location interaction in most traits. In the coastal trial, trees formed narrower vessels and stored more starch before inoculation. The synchrony of leaf phenology, higher growth rate, lower starch reserves and higher structural vulnerability of earlywood to DED possibly favored susceptibility in the inland plot. The varying responses of genotypes in phenology, growth and anatomy at both locations were likely related to the differences in DED resistance, which can have important consequences for elm reintroduction.

中文翻译：

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荷兰榆树病抗性中的基因型-环境相互作用


荷兰榆树病 （DED） 是一种毁灭性的森林病害。最近，本地抗性栽培品种的部署促使欧洲和北美重新引入榆树。众所周知，DED 抗性随树木基因型而变化，并受气候因素的影响。然而，DED 耐药性中的基因型与环境的相互作用在很大程度上仍未得到探索。在这项工作中，我们检查了 DED 抗性可塑性是否存在遗传变异，以及树木生长、物候和解剖性状在塑料反应中的作用。我们在西班牙的两个环境对比鲜明的地方建立了两个具有 12 种 Ulmus 次要基因型的实验地：内陆大陆性气候下的马德里和沿海地中海气候下的瓦伦西亚。我们监测了生长和物候学，检测到这两个性状的高可塑性。在内陆样地中，基因型比沿海地块更高，物候学更同步。在每个地点的平均冲洗日期后 45 天进行第一次 DED 病原体接种，之后树木在内陆表现出更多的症状。通过将沿海地块树木分为早冲洗树和晚冲洗树，并在平均冲洗日期后 45 天接种每组进行第二次接种。其中，易感性上升到接近内陆地块的水平。在两次接种中，我们检测到 DED 耐药性中存在显着的基因型-位置相互作用。木质部解剖结构显示，在大多数性状中，高可塑性和显着的基因型-位置相互作用。在沿海试验中，树木在接种前形成更窄的血管并储存更多的淀粉。 早材叶片物候的同步性、较高的生长速率、较低的淀粉储量和较高的结构易损性 DED 可能有利于内陆样地的易感性。两个位置基因型在物候、生长和解剖学中的不同反应可能与 DED 抗性差异有关，这可能对榆树重新引入产生重要影响。