ABSTRACT

Historical results from provenance trials tended to position Sudetan larch (Larix decidua Mill. sudetica) populations among the least susceptible to larch canker (Lachnellula willkommi (R.Hartig) Dennis), in sharp contrast to Alpine populations. However, a recent large-scale outbreak of larch canker in artificial French stands planted with Sudetan larch brings into question this conclusion but also, as a consequence, the value of Sudetan larch seed orchards to mass-propagate risk-limited forest reproductive material. Clonal material from the French breeding population and seed orchards was investigated for its susceptibility to larch canker. As a first step, a genetic structure analysis of this population (220 clones) was conducted: it revealed its genetic heterogeneity, with 53.1% of the clones classified as “pure” Sudetan, 3.1% as Alpine; 1.5% as Central European and 42.3% as introgressed. Following artificial inoculation, “pure” Sudetan clones appeared generally less susceptible to canker than Alpine clones; admixed clones behaved in a similar way to the pure Sudetan material. However, the broad clonal variability observed within each population prevents the sole use of genetic origin of clones to rogue the most susceptible ones within orchards. Artificial inoculation is, so far, the only reliable way to properly assess clonal behaviour towards canker and thus support genetic roguing of orchards.

摘要

起源试验的历史结果倾向于将苏台德落叶松 ( Larix decidua Mill. s udetica ) 种群定位于最不容易感染落叶松溃疡病 ( Lachnellula willkommi (R.Hartig) Dennis), 与高山种群形成鲜明对比。然而，最近在种植有苏台德落叶松的法国人工林中大规模爆发落叶松溃疡病使这一结论受到质疑，因此也质疑苏台德落叶松种子园大规模繁殖风险有限的森林繁殖材料的价值。研究了来自法国繁殖种群和种子园的克隆材料对落叶松溃疡病的易感性。作为第一步，对该种群（220 个克隆）进行了遗传结构分析：它揭示了其遗传异质性，其中 53.1% 的克隆被归类为“纯”苏台德人，3.1% 为阿尔卑斯山；1.5% 为中欧人，42.3% 为渐渗人。人工接种后，“纯”苏台德克隆人似乎比阿尔卑斯山克隆人更不易患溃疡病；混合克隆的表现与纯苏德坦材料相似。然而，在每个种群中观察到的广泛克隆变异性阻止了单独使用克隆的遗传起源来欺骗果园中最易感的克隆。到目前为止，人工接种是正确评估对溃疡病的克隆行为并因此支持果园遗传流氓的唯一可靠方法。