Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa.
Mycologia. 2002 Nov-Dec;94(6):1032-43.
Fusarium isolates that form part of the Gibberella fujikuroi species complex have been classified using either a morphological, biological, or phylogenetic species concept. Problems with the taxonomy of Fusarium species in this complex are mostly experienced when the morphological and biological species concepts are applied. The most consistent identifications are obtained with the phylogenetic species concept. Results from recent studies have presented an example of discordance between the biological and phylogenetic species concepts, where a group of F. subglutinans sensu stricto isolates, i.e., isolates belonging to mating population E of the G. fujikuroi complex, could be sub-divided into more than one phylogenetic lineage. The aim of this study was to determine whether this sub-division represented species divergence or intraspecific diversity in F. subglutinans. For this purpose, we included 29 F. subglutinans isolates belonging to the E-mating population that were collected from either maize or teosinte, from a wide geographic range. DNA sequence data for six nuclear regions in each of these isolates were obtained and used in phylogenetic concordance analyses. These analyses revealed the presence of two major groups representing cryptic species in F. subglutinans. These cryptic species were further sub-divided into a number of smaller groups that appear to be reproductively isolated in nature. This suggests not only that the existing F. subglutinans populations are in the process of divergence, but also that each of the resulting lineages are undergoing separation into distinct taxa. These divergences did not appear to be linked to geographic origin, host, or phenotypic characters such as morphology.
属于藤仓赤霉种复合体的镰刀菌分离株曾采用形态学、生物学或系统发育种概念进行分类。在应用形态学和生物学种概念时，该复合体中镰刀菌的分类学问题最为突出。采用系统发育种概念时，最能获得一致性的鉴定结果。最近的研究结果呈现了生物学种概念和系统发育种概念之间的不一致性的实例，即严格意义上的 F. subglutinans 群的一组 F. subglutinans 分离株，即属于藤仓赤霉复合体 E 交配群的分离株，可进一步细分为一个以上的系统发育谱系。本研究旨在确定这种细分是否代表 F. subglutinans 中的物种分化或种内多样性。为此，我们从广泛的地理范围收集了来自玉米或类蜀黍的属于 E 交配群的 29 株 F. subglutinans 分离株，并获得了这些分离株中每个 6 个核区的 DNA 序列数据，然后用于系统发育一致性分析。这些分析揭示了 F. subglutinans 中存在两个代表隐种的主要群体。这些隐种进一步细分为一些较小的群体，这些群体在自然界中似乎是生殖隔离的。这不仅表明现有的 F. subglutinans 种群正在发生分化，而且还表明每个由此产生的谱系都在向不同的分类单元分离。这些分歧似乎与地理起源、宿主或表型特征（如形态）无关。
