Data from: Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems

Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination 6-fold. Our findings have important implications for seagrass ecology, because these putative pathogens likely negatively affect ecosystem functioning, as well as current restoration and conservation efforts.疫霉属（Phytophthora）物种是极具侵染力的陆生植物病原菌，每年给农业作物造成数十亿美元的经济损失，并对全球范围内的脆弱陆地生态系统造成破坏。然而，人们对其海洋近缘类群的分布与致病性却几乎一无所知。这一现状颇为意外，因为海洋植物是全球沿岸带（如红树林、盐沼、海草床）的关键栖息地，而病害可能是这些快速衰退的生态系统在保护与修复工作中面临的重要瓶颈。本研究首次报道了北大西洋与地中海沿岸的常见海草物种——大叶藻（Zostera marina，又称鳗草）广泛感染疫霉属与海疫霉属（Halophytophthora）物种的情况。此外，我们在多种环境条件下开展完全析因实验室实验，探究海疫霉未定种（Halophytophthora sp.）Zostera与双子疫霉（Phytophthora gemini）对大叶藻种子萌发的影响。研究结果显示，疫霉属物种分布广泛：我们在北大西洋与地中海沿岸6个国家的海草床中均检测到了这类卵菌。海疫霉未定种Zostera、双子疫霉，或二者共同侵染，均可使大叶藻种子萌发率降低6倍，显著抑制其有性生殖过程。本研究发现对海草生态学具有重要意义：这类潜在病原菌可能对生态系统功能产生负面影响，同时也会对当前的海草修复与保护工作造成不利影响。