Sainsbury Laboratory Cambridge University (SLCU), Cambridge, United Kingdom
Sainsbury Laboratory Cambridge University (SLCU), Cambridge, United Kingdom.
mBio. 2019 Oct 1;10(5):e01516-19. doi: 10.1128/mBio.01516-19.
Multinucleate fungi and oomycetes are phylogenetically distant but structurally similar. To address whether they share similar nuclear dynamics, we carried out time-lapse imaging of fluorescently labeled nuclei. Nuclei underwent coordinated bidirectional movements during plant infection. Within hyphal networks growing or in axenic culture, nuclei either are dragged passively with the cytoplasm or actively become rerouted toward nucleus-depleted hyphal sections and often display a very stretched shape. Benomyl-induced depolymerization of microtubules reduced active movements and the occurrence of stretched nuclei. A centrosome protein localized at the leading end of stretched nuclei, suggesting that, as in fungi, astral microtubule-guided movements contribute to nuclear distribution within oomycete hyphae. The remarkable hydrodynamic shape adaptations of nuclei contrast with those in fungi and likely enable them to migrate over longer distances. Therefore, our work summarizes mechanisms which enable a near-equal nuclear distribution in an oomycete. We provide a basis for computational modeling of hydrodynamic nuclear deformation within branched tubular networks. Despite their fungal morphology, oomycetes constitute a distinct group of protists related to brown algae and diatoms. Many oomycetes are pathogens and cause diseases of plants, insects, mammals, and humans. Extensive efforts have been made to understand the molecular basis of oomycete infection, but durable protection against these pathogens is yet to be achieved. We use a plant-pathogenic oomycete to decipher a key physiological aspect of oomycete growth and infection. We show that oomycete nuclei travel actively and over long distances within hyphae and during infection. Such movements require microtubules anchored on the centrosome. Nuclei hydrodynamically adapt their shape to travel in or against the flow. In contrast, fungi lack a centrosome and have much less flexible nuclei. Our findings provide a basis for modeling of flexible nuclear shapes in branched hyphal networks and may help in finding hard-to-evade targets to develop specific antioomycete strategies and achieve durable crop disease protection.
多核真菌和卵菌在系统发育上相距甚远，但在结构上却非常相似。为了研究它们是否具有相似的核动力学，我们对荧光标记的核进行了延时成像。在植物感染过程中，核经历了协调的双向运动。在生长中的菌丝网络或在无菌培养中，核要么随细胞质被动拖动，要么主动转向核耗竭的菌丝段，并经常呈现出非常伸展的形状。苯并咪唑诱导的微管解聚减少了主动运动和伸展核的发生。一种定位于伸展核前端的中心体蛋白表明，与真菌一样，星状微管引导的运动有助于卵菌菌丝内核的分布。细胞核显著的流体动力形状适应与真菌中的形状适应形成对比，可能使它们能够长距离迁移。因此，我们的工作总结了使卵菌中核近等分布的机制。我们为分支管状网络中流体动力核变形的计算建模提供了基础。尽管卵菌具有真菌形态，但它们是与褐藻和硅藻相关的一个独特的原生生物群。许多卵菌是病原体，会导致植物、昆虫、哺乳动物和人类患病。人们已经做出了大量努力来理解卵菌感染的分子基础，但仍未实现对这些病原体的持久保护。我们使用一种植物病原卵菌来破译卵菌生长和感染的一个关键生理方面。我们表明，卵菌核在菌丝内和感染过程中主动且长距离迁移。这种运动需要中心体上锚定的微管。细胞核通过流体动力学改变形状以在流动中或逆流中移动。相比之下，真菌没有中心体，核的柔韧性也差得多。我们的发现为分支菌丝网络中灵活核形状的建模提供了基础，并可能有助于找到难以回避的靶点，以开发特定的抗卵菌策略并实现持久的作物疾病保护。
