Nationaal Herbarium Nederland, Universiteit Leiden branch, Phanerogams and Cryptogams of the Netherlands and Europe section, P.O. Box 9514, 2300 RA Leiden, The Netherlands.
Mycologia. 2004 Jan-Feb;96(1):102-18.
Phylogenetic relationships of the European species of Leccinum (Boletales, Boletaceae) were investigated by maximum parsimony, Bayesian and likelihood analyses of nrITS1-5.8S-ITS2 and 28S sequences. The separate gene trees inferred were largely concordant, and their combined analysis indicates that several traditional sectional and species-level taxonomic schemes are artificial. In Leccinum, the nrITS region ranges in size from 694 to 1480 bp. This extreme length heterogeneity is localized to a part of the ITS1 spacer that contains a minisatellite characterized by the repeated presence of CTATTGAAAAG and CTAATAGAAAG core sequences and mutational derivatives thereof. The number of core sequences present in the minisatellite varied from 12 to 36. Intra-individual sequence variation of the minisatellite was always smaller than between different species, indicating that concerted evolution proceeds rapidly enough to retain phylogenetic signal at the infraspecific level. In contrast, the evolutionary pattern exhibited by the major ITS1 repeat types found was homoplastic when mapped onto the species lineages inferred from the combined 5.8S-ITS2 sequences. The minisatellite therefore appears not to be useful for phylogeny reconstruction at or above the species level.
通过最大简约法、贝叶斯法和似然法对 nrITS1-5.8S-ITS2 和 28S 序列进行分析，研究了欧洲乳菇属（牛肝菌目，牛肝菌科）物种的系统发育关系。推断出的独立基因树在很大程度上是一致的，它们的联合分析表明，一些传统的分类和种级别的分类方案是人为的。在乳菇属中，nrITS 区大小从 694bp 到 1480bp 不等。这种极端的长度异质性局限于 ITS1 间隔区的一部分，其中包含一个微卫星，其特征是反复出现 CTATTGAAAAG 和 CTAATAGAAAG 核心序列及其突变衍生物。微卫星中存在的核心序列数量从 12 到 36 不等。微卫星的个体内序列变异总是小于不同物种之间的序列变异，这表明协同进化足够迅速，足以在种内水平保留系统发育信号。相比之下，当映射到从 5.8S-ITS2 序列推断出的物种谱系上时，发现的主要 ITS1 重复类型的进化模式是同形的。因此，微卫星似乎不适用于种级或以上水平的系统发育重建。
