Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
Institute of Botany at The Lithuanian State Research Institute Nature Research Centre, Žaliųjų Ežerų Str. 49, LT-08406 Vilnius, Lithuania.
Phytopathology. 2020 Dec;110(12):1959-1969. doi: 10.1094/PHYTO-12-19-0475-R. Epub 2020 Oct 28.
In pathogenic fungi and oomycetes, interspecific hybridization may lead to the formation of new species having a greater impact on natural ecosystems than the parental species. From the early 1990s, a severe alder ( spp.) decline due to an unknown species was observed in several European countries. Genetic analyses revealed that the disease was caused by the triploid hybrid × , which originated in Europe from the hybridization of and × . Here, we investigated the population structure of × (158 isolates) and (85 isolates) in several European countries using microsatellite markers. Our analyses confirmed the genetic structure previously observed in other European populations, with populations consisting of at most two multilocus genotypes (MLGs) and × populations dominated by MLG Pxa-1. The genetic structure of × populations in the Czech Republic, Hungary and Sweden seemed to reflect the physical isolation of river systems. Most rare × MLGs showed a loss of heterozygosity (LOH) at one or a few microsatellite loci compared with other MLGs. This LOH may allow a stabilization within the × genome or a rapid adaptation to stress situations. Alternatively, alleles may be lost because of random genetic drift in small, isolated populations, with no effect on fitness of × . Additional studies would be necessary to confirm these patterns of population diversification and to better understand the factors driving it.
在病原真菌和卵菌中，种间杂交可能导致形成新物种，这些新物种对自然生态系统的影响比亲本物种更大。从 20 世纪 90 年代初开始，在几个欧洲国家观察到一种未知物种导致桤木（ spp.）严重衰退。遗传分析表明，这种疾病是由三倍体杂种 × 引起的，它起源于欧洲，是由 和 × 的杂交产生的。在这里，我们使用微卫星标记研究了几种欧洲国家的 × （158 个分离株）和 （85 个分离株）的种群结构。我们的分析证实了先前在其他欧洲种群中观察到的遗传结构，其中 种群最多由两个多位点基因型（MLG）组成，而 × 种群则由 MLG Pxa-1 主导。捷克共和国、匈牙利和瑞典的 × 种群的遗传结构似乎反映了水系的物理隔离。与其他 MLG 相比，大多数罕见的 × MLG 在一个或几个微卫星位点上显示出杂合性丢失（LOH）。这种 LOH 可能允许在 × 基因组内稳定或快速适应应激情况。或者，等位基因可能会因为小而孤立的种群中的随机遗传漂变而丢失，而不会对 × 的适合度产生影响。需要进一步的研究来证实这些种群多样化的模式，并更好地理解驱动这些模式的因素。
