Kieler Wirkstoff-Zentrum, Helmholtz Centre for Ocean Research GEOMAR, Kiel, Schleswig-Holstein, Germany.
PLoS One. 2012;7(9):e45358. doi: 10.1371/journal.pone.0045358. Epub 2012 Sep 17.
Durvillaea antarctica (Fucales, Phaeophyceae) is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean), abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria) was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on 'the strongest seaweed of the world', which is an important habitat forming and economic resource from the Southern Hemisphere.
南极厚叶藻（Fucales，Phaeophyceae）是南半球具有重要生态和经济意义的大型巨藻。在智利中部海岸（太平洋）的天然床中，观察到异常生长的特征是明显的瘿瘤发育和叶状体/藻体变色。通过光学显微镜和扫描电子显微镜分析这些瘿瘤，发现存在内生真核生物，表现出典型的植蝇类寄生虫特征。寄生虫在宿主的皮层组织下的扩大细胞内发育。多核质体发育成许多单个休眠孢子。18S rDNA 数据支持这种寄生虫与植蝇类（Rhizaria）的亲缘关系，将其置于 Phagomyxida 中。类似的微生物在 23 年前曾被报道过一次，表明这些寄生虫在南极厚叶藻床中持久且广泛存在了很长时间。本文还讨论了这种寄生虫引起的症状以及其对生态和经济的影响。植蝇类寄生虫可能在海洋生态系统中发挥重要作用，但在这种环境中，它们的研究仍相对较少。我们的研究结果首次证明了 Phagomyxida 中休眠孢子的存在，在这个目里，人们认为不存在休眠孢子，这使得该寄生虫成为迄今为止第一个具有完整生命周期的植蝇类寄生虫的记录，这挑战了植蝇类中的现有分类概念。本文将讨论所描述的休眠孢子对食菌体寄生虫的生存和生态学的重要性，以及这种寄生虫可能对“世界上最强壮的海藻”产生的影响，这种海藻是南半球重要的栖息地形成和经济资源。
