Diversity and host specificity of the oomycete-parasitic oomycete genus Olpidiopsis

Olpidiopsis属属于卵菌的早期分化谱系，包含十多个寄生于卵菌的种。在Olpidiopsis的宿主中，有几个经济上相关的卵菌属，如隐菌属（Aphanomyces）、霉属（Pythium）和霉属（Saprolegnia）。然而，Olpidiopsis属的物种不能离开它们的活宿主而生存，这就需要首先培养一个合适的宿主，然后才能用来繁殖和诱饵Olpidiopsis物种。然而，这个复杂的过程并没有进行很长一段时间，直到我们最近把一些种类的Olpidiopsis与它们各自的宿主进行双重培养。尽管在这些初步测试中，所描述的物种中只有少数能够被分离出来，但已经发现了意想不到的多样性，导致描述了一个新物种，并且在一项未发表的研究中，该属的另外两个物种可以被分离出来。这表明我们所开发的方法在分离该属的物种方面是非常有效的。在此基础上，本研究的主要目标是分离广谱的Olpidiopsis物种，以验证三个主要假设：1)Olpidiopsis物种的多样性比目前已知的要多得多；2)Olpidiopsis物种的组成和丰富度受栖息地的强烈影响；3)Olpidiopsis物种具有高度的宿主特异性。这些假设将通过诱饵、建立双重培养、交叉感染实验、环境测序和系统发育来检验。该研究结果将为了解卵菌寄生属Olpidiopsis的进化和生态学带来根本性的进展，该属是植物和动物中卵菌引起的疾病的潜在调节剂。随着双培养的建立，一些下游研究方向将成为可能，例如解剖卵菌寄生虫及其卵菌宿主的分子相互作用，以及测试Olpidiopsis菌株作为生物防治剂防治重要的卵菌引起的疾病，如铅诱导的幼苗衰减，小龙虾鼠疫和鱼类腐殖病。

The genus Olpidiopsis belongs to the early-diverging lineages of the oomycetes and contains more than a dozen species parasitic to oomycetes. Among the hosts of Olpidiopsis are several economically relevant oomycete genera, such as Aphanomyces, Pythium, and Saprolegnia. However, species of the genus Olpidiopsis cannot live without their living host, which makes it necessary to first grow a suitable host, which then can be used to propagate and bait Olpidiopsis species. However, this complicated procedure has not been carried out for a long time, until we have recently brought a few species of Olpidiopsis into dual culture with their respective hosts.Even though in these preliminary tests only few of the described species could be isolated, there was already an unexpected diversity found, leading to the description of one new species, and in an unpublished study two additional species of the genus could be isolated. This suggests that the methodology we have developed is highly efficient in isolating species of the genus. On the basis of these advances, we are now aiming in the proposed research to isolate a wide spectrum of Olpidiopsis species, to test three main hypotheses – 1) Olpidiopsis species are much more diverse than currently known, 2) Olpidiopsis species composition and richness is strongly influenced by the habitat, 3) Olpidiopsis species are highly host specific. These hypotheses will be tested using baiting, establishment of dual cultures, cross-infection experiments, environmental sequencing and phylogenetics.The findings of the proposed research will lead to fundamental progress with respect to understand the evolution and ecology of the oomycete-parasitic genus Olpidiopsis, which is a potential regulator of oomycete-caused diseases in plants and animals. With the establishment of dual cultures, several downstream research lines will become feasible, such as dissecting the molecular interaction of oomycete parasites and their oomycete hosts, as well as the testing of Olpidiopsis strains as biocontrol agent against important oomycete-caused diseases, such as Pythium-induced damping off of seedlings, crayfish plague and saprolegniosis in fish.