Faculty of Biology, Department of Plant Taxonomy and Nature Conservation, University of Gdańsk, ul. Wita Stwosza 59, 80-308, Gdańsk, Poland.
Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdansk, Poland.
J Plant Res. 2022 Mar;135(2):275-293. doi: 10.1007/s10265-021-01364-7. Epub 2022 Jan 6.
Some plants abandoned photosynthesis and developed full dependency on fungi for nutrition. Most of the so-called mycoheterotrophic plants exhibit high specificity towards their fungal partners. We tested whether natural rarity of mycoheterotrophic plants and usual small and fluctuating population size make their populations more prone to genetic differentiation caused by restricted gene flow and/or genetic drift. We also tested whether these genetic characteristics might in turn shape divergent fungal preferences. We studied the mycoheterotrophic orchid Epipogium aphyllum, addressing the joint issues of genetic structure of its populations over Europe and possible consequences for mycorrhizal specificity within the associated fungal taxa. Out of 27 sampled E. aphyllum populations, nine were included for genetic diversity assessment using nine nuclear microsatellites and plastid DNA. Population genetic structure was inferred based on the total number of populations. Individuals from 17 locations were included into analysis of genetic identity of mycorrhizal fungi of E. aphyllum based on barcoding by nuclear ribosomal DNA. Epipogium aphyllum populations revealed high genetic diversity (uHe = 0.562) and low genetic differentiation over vast distances (F = 0.106 for nuclear microsatellites and F = 0.156 for plastid DNA). Bayesian clustering analyses identified only two genetic clusters, with a high degree of admixture. Epipogium aphyllum genets arise from panmixia and display locally variable, but relatively high production of ramets, as shown by a low value of rarefied genotypic richness (R = 0.265). Epipogium aphyllum genotype control over partner selection was negligible as (1) we found ramets from a single genetic individual associated with up to 68% of the known Inocybe spp. associating with the plant species, (2) and partner identity did not show any geographic structure. The absence of mosaicism in the mycorrhizal specificity over Europe may be linked to preferential allogamous habit of E. aphyllum and significant gene flow, which tend to promote host generalism.
一些植物放弃了光合作用，完全依赖真菌获取营养。大多数所谓的菌根异养植物对其真菌伙伴表现出高度的特异性。我们测试了菌根异养植物的自然稀有性以及通常较小且波动的种群规模是否会导致其种群更容易受到限制基因流动和/或遗传漂变引起的遗传分化。我们还测试了这些遗传特征是否会反过来塑造不同的真菌偏好。我们研究了菌根异养兰花 Epipogium aphyllum，探讨了其在欧洲的种群遗传结构问题以及与相关真菌分类群的共生特异性的可能后果。在 27 个采样的 E. aphyllum 种群中，有 9 个种群被纳入使用 9 个核微卫星和质体 DNA 进行遗传多样性评估。基于种群总数推断了种群遗传结构。来自 17 个地点的个体被纳入基于核核糖体 DNA 条形码的 E. aphyllum 共生真菌遗传同一性分析。Epipogium aphyllum 种群表现出高遗传多样性（uHe=0.562）和跨越广阔距离的低遗传分化（核微卫星为 F=0.106，质体 DNA 为 F=0.156）。贝叶斯聚类分析仅识别出两个遗传聚类，具有高度的混合。Epipogium aphyllum 遗传体来自泛化交配，表现出局部可变但相对较高的分株产生，这可以通过较低的稀有基因型丰富度值（R=0.265）来证明。Epipogium aphyllum 对伙伴选择的基因型控制可以忽略不计，因为 (1) 我们发现来自单个遗传个体的分株与多达 68%的已知 Inocybe spp. 相关联，这些 Inocybe spp. 与植物物种相关联，(2) 并且伙伴身份没有显示出任何地理结构。欧洲菌根特异性的非镶嵌现象可能与 E. aphyllum 的优先异花授粉习性和显著的基因流有关，这有助于促进宿主的普遍性。
