Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Institute of Botany, Justus Liebig University, Gießen, Germany.
Fungal Biol. 2020 Sep;124(9):781-800. doi: 10.1016/j.funbio.2020.06.001. Epub 2020 Jul 17.
Despite multiple taxonomic revisions, several uncertainties at the genus and species level remain to be resolved within the Serendipitaceae family (Sebacinales). This volatile classification is attributed to the limited number of available axenic cultures and the scarcity of useful morphological traits. In the current study, we attempted to discover alternative taxonomic markers not relying on DNA sequences to differentiate among the closely related members of our Congolese Serendipita isolate collection and the reference strains S. indica (syn. Piriformospora indica) and S. williamsii (syn. P. williamsii). We demonstrated that nuclear distribution across hyphal cells and genome size (determined by flow cytometry) did not have enough resolving power, but quantitative and qualitative variations in the ultrastructure of the dolipore septa investigated by transmission electron microscopy did provide useful markers. Multivariate analysis revealed that subtle differences in ultrastructural characteristics of the parenthesome and the attached endoplasmic reticulum are most relevant when studying this fungal group. Moreover, the observed clustering pattern showed that there might be more diversity amongst the Congolese isolates within the S. 'williamsii' species complex than previously anticipated based on molecular data. Altogether, our results provide novel perspectives on the use of integrative approaches to support sebacinoid and Serendipitaceae taxonomy.
尽管已经进行了多次分类修订，但在 Sebacinales（指疫霉科）内的属和种水平仍存在一些不确定性需要解决。这种不稳定的分类归因于可用的纯培养物数量有限，以及有用形态特征的稀缺。在本研究中，我们试图发现不依赖 DNA 序列的替代分类标记，以区分我们的刚果塞兰迪皮塔分离物集和参考菌株 S. indica（同义词：Piriformospora indica）和 S. williamsii（同义词：P. williamsii）之间的密切相关成员。我们证明了核在菌丝细胞中的分布和基因组大小（通过流式细胞术确定）没有足够的分辨率，但通过透射电子显微镜研究的质膜孔隔的超微结构的定量和定性变化提供了有用的标记。多变量分析表明，在研究这个真菌群时，质体和附着的内质网的超微结构特征的细微差异最为重要。此外，观察到的聚类模式表明，基于分子数据，在 S. 'williamsii'种复合体中，刚果分离物之间的多样性可能比预期的要多。总之，我们的结果为支持 sebacinoid 和 Serendipitaceae 分类学的综合方法提供了新的视角。
