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 sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.疫霉属（Phytophthora）物种是一类强致病性病原菌，可损毁陆生植物，每年给农业作物造成数十亿美元的经济损失，并损害全球各地的脆弱生态系统。然而，人们对其海洋近缘类群的分布与致病性几乎一无所知。这一现状令人意外，因为海洋植物在全球沿海区域构成了至关重要的栖息地（如红树林、盐沼、海草床），而病害可能是这些快速衰退的生态系统的保护与修复面临的重要瓶颈。本研究首次报道了疫霉属与海疫霉属（Halophytophthora）物种在北大西洋北部及地中海区域的常见海草物种——大叶藻（Zostera marina，俗称鳗草）上的广泛侵染现象。此外，本研究在多种环境条件下开展全因子实验室实验，探究了海疫霉属未定种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：我们在北大西洋北部及地中海区域的六个国家的鳗草床中均检测到了这类卵菌（oomycetes）。海疫霉属未定种Zostera、双子疫霉，或二者共同侵染，均会使大叶藻种子萌发率降至初始水平的1/6，显著抑制其有性生殖过程。本研究结果对海草生态学具有重要的启示意义：这类推定的病原菌可能会对生态系统功能造成负面影响，同时也会干扰当前的海草生态修复与保护工作。