Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, USA.
Mol Phylogenet Evol. 2010 Dec;57(3):1276-92. doi: 10.1016/j.ympev.2010.10.004. Epub 2010 Oct 21.
Porcini (Boletus section Boletus: Boletaceae: Boletineae: Boletales) are a conspicuous group of wild, edible mushrooms characterized by fleshy fruiting bodies with a poroid hymenophore that is "stuffed" with white hyphae when young. Their reported distribution is with ectomycorrhizal plants throughout the Northern Hemisphere. Little progress has been made on the systematics of this group using modern molecular phylogenetic tools because sampling has been limited primarily to European species and the genes employed were insufficient to resolve the phylogeny. We examined the evolutionary history of porcini by using a global geographic sampling of most known species, new discoveries from little explored areas, and multiple genes. We used 78 sequences from the fast-evolving nuclear internal transcribed spacers and are able to recognize 18 reciprocally monophyletic species. To address whether or not porcini form a monophyletic group, we compiled a broadly sampled dataset of 41 taxa, including other members of the Boletineae, and used separate and combined phylogenetic analysis of sequences from the nuclear large subunit ribosomal DNA, the largest subunit of RNA polymerase II, and the mitochondrial ATPase subunit six gene. Contrary to previous studies, our separate and combined phylogenetic analyses support the monophyly of porcini. We also report the discovery of two taxa that expand the known distribution of porcini to Australia and Thailand and have ancient phylogenetic connections to the rest of the group. A relaxed molecular clock analysis with these new taxa dates the origin of porcini to between 42 and 54 million years ago, coinciding with the initial diversification of angiosperms, during the Eocene epoch when the climate was warm and humid. These results reveal an unexpected diversity, distribution, and ancient origin of a group of commercially valuable mushrooms that may provide an economic incentive for conservation and support the hypothesis of a tropical origin of the ectomycorrhizal symbiosis.
牛肝菌（Boletus 属：牛肝菌科：牛肝菌亚科：牛肝菌目）是一类显著的野生食用菌，其肉质的子实体具有多孔的子实层，在年轻时，其子实层被白色菌丝填充。它们的分布范围是北半球的外生菌根植物。由于采样主要局限于欧洲物种，并且使用的基因不足以解决系统发育问题，因此，使用现代分子系统发育工具在该类群的系统发育方面几乎没有取得进展。我们通过对大多数已知物种进行全球地理采样、对来自探索较少地区的新发现进行采样，以及使用多个基因，研究了牛肝菌的进化历史。我们使用了快速进化的核内转录间隔区的 78 个序列，能够识别出 18 个相互单系的物种。为了解牛肝菌是否形成单系群，我们编译了一个广泛采样的数据集，其中包括牛肝菌亚科的其他成员，并使用核大亚基核糖体 DNA、RNA 聚合酶 II 最大亚基和线粒体 ATP 合酶亚基六基因的序列进行单独和联合的系统发育分析。与之前的研究相反，我们的单独和联合系统发育分析支持牛肝菌的单系性。我们还报告了两个新发现的物种，它们将牛肝菌的已知分布范围扩大到了澳大利亚和泰国，并与该组的其他成员具有古老的进化联系。对这些新发现的物种进行放松的分子钟分析，表明牛肝菌的起源时间在 4200 万至 5400 万年前之间，与被子植物的最初多样化时间相吻合，这一时期处于始新世，气候温暖潮湿。这些结果揭示了一组具有商业价值的蘑菇的出乎意料的多样性、分布和古老起源，这可能为保护提供经济激励，并支持外生菌根共生关系起源于热带的假说。
