Department of Botany and Plant Pathology, Purdue University, 915 W State St, West Lafayette, IN 47907-2054, USA.
Department of Botany and Plant Pathology, Purdue University, 915 W State St, West Lafayette, IN 47907-2054, USA.
Fungal Genet Biol. 2021 Jul;152:103565. doi: 10.1016/j.fgb.2021.103565. Epub 2021 May 13.
Fungal dimorphism is a phenomenon by which a fungus can grow both as a yeast form and a hyphal form. It is frequently related to pathogenicity as different growth forms are more suitable for different functions during a life cycle. Among dimorphic plant pathogens, the corn smut fungus Ustilago maydis serves as a model organism to understand fungal dimorphism and its effect on pathogenicity. However, there is a lack of data on whether mechanisms elucidated from model species are broadly applicable to other fungi. In this study, two non-model plant-associated species in the smut fungus subphylum (Ustilaginomycotina), Tilletiopsis washingtonensis and Meira miltonrushii, were selected to compare dimorphic mechanisms in these to those in U. maydis. We sequenced transcriptomic profiles during both yeast and hyphal growth in these two species using Tween40, a lipid mimic, as a trigger for hyphal growth. We then compared our data with previously published data from U. maydis and a fourth but unrelated dimorphic phytopathogen, Ophiostoma novo-ulmi. Comparative transcriptomics was performed to identify common genes upregulated during hyphal growth in all four dimorphic species. Intriguingly, T. washingtonensis shares the least similarities of transcriptomic alteration (hyphal growth versus yeast growth) with the others, although it is closely related to M. miltonrushii and U. maydis. This suggests that phylogenetic relatedness is not correlated with transcriptomic similarity under the same biological phenomenon. Among commonly expressed genes in the four species, genes in cell energy production and conversion, amino acid transport and metabolism and cytoskeleton are significantly enriched. Considering dimorphism genes characterized in U. maydis, as well as hyphal tip-associated genes from the literature, we found only genes encoding the cell end marker Tea4/TeaC and the kinesin motor protein Kin3 concordantly expressed in all four species. This suggests a divergence in species-specific mechanisms for dimorphic transition and hyphal growth.
真菌的二相性是指一种真菌可以同时生长为酵母形态和菌丝形态。它通常与致病性有关，因为不同的生长形态在生命周期的不同功能中更为合适。在二相性植物病原体中，玉米黑粉菌 Ustilago maydis 是一种模式生物，用于理解真菌的二相性及其对致病性的影响。然而，目前还缺乏关于从模式物种中阐明的机制是否广泛适用于其他真菌的信息。在这项研究中，选择了黑粉菌亚门（Ustilaginomycotina）中的两种非模式植物相关物种，即 Tilletiopsis washingtonensis 和 Meira miltonrushii，以比较这两种物种与 U. maydis 的二相性机制。我们使用吐温 40（一种脂质类似物）作为触发菌丝生长的诱导剂，对这两个物种在酵母和菌丝生长过程中的转录组图谱进行了测序。然后，我们将我们的数据与之前从 U. maydis 和第四种但不相关的二相性植物病原体 Ophiostoma novo-ulmi 发表的数据进行了比较。进行比较转录组学分析，以鉴定在所有四个二相性物种中菌丝生长过程中上调的共同基因。有趣的是，尽管 T. washingtonensis 与 M. miltonrushii 和 U. maydis 密切相关，但它与其他物种的菌丝生长转录组变化（酵母生长与菌丝生长）相似度最低。这表明系统发育上的亲缘关系与同一生物学现象下的转录组相似性没有相关性。在这四个物种中共同表达的基因中，细胞能量产生和转化、氨基酸转运和代谢以及细胞骨架相关的基因显著富集。考虑到 U. maydis 中特征化的二相性基因，以及文献中菌丝尖端相关基因，我们发现只有编码细胞末端标记 Tea4/TeaC 和驱动蛋白运动蛋白 Kin3 的基因在所有四个物种中一致表达。这表明在物种特异性的二相性转变和菌丝生长机制中存在分歧。
