Purpose of Review

Because tree seeds have been considered a low-risk pathway for the spread of plant pathogenic fungi, their international movement is not subject to strict phytosanitary regulation. However, recent studies have provided scientific evidence that the biosecurity risk of seed trade may not be as negligible as assumed. This review summarises current knowledge about seed trade activity across the world and seed-borne plant pathogenic fungi and highlights knowledge gaps that need to be filled to mitigate the risk of spreading tree pathogens via seeds.

Recent Findings

Several outbreaks of severe tree diseases in natural forests and plantations worldwide have been linked to fungal pathogens spread by seed trade. Indeed, recent studies based on modern sequencing technologies have shown that tree seeds harbour highly diverse fungal communities, including well-known pathogens and fungal taxa belonging to unknown species. While it has become clear that even apparently healthy seeds can carry potentially pathogenic fungi, the likelihood of seed-borne pathogens being introduced and becoming established, spreading and causing impact in the new environment is still unclear which challenges the assessment of the phytosanitary risk posed by seed trade.

Summary

Our analyses show that large amounts of tree seeds have been traded among countries and continents. Based on published literature, the risk of spreading pathogenic fungi via tree seed movement is high. However, the role of the taxonomically and functionally diverse fungal communities associated with seeds is still poorly understood. In particular, more research is needed to assess the likelihood of seed-borne fungi being transmitted to the seedlings and spreading and causing impact in the new environment.

中文翻译：

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国际林木种子流动的生物安全风险

审查目的

由于树木种子被认为是植物病原真菌传播的低风险途径，因此它们的国际流动不受严格的植物检疫监管。然而，最近的研究提供了科学证据，表明种子贸易的生物安全风险可能并不像假设的那样可以忽略不计。本综述总结了有关世界各地种子贸易活动和种子传播植物病原真菌的最新知识，并强调了需要填补的知识空白，以减轻通过种子传播树木病原体的风险。

最近的发现

世界各地天然林和种植园中发生的几起严重树木病害的爆发与种子贸易传播的真菌病原体有关。事实上，最近基于现代测序技术的研究表明，树木种子蕴藏着高度多样化的真菌群落，包括众所周知的病原体和属于未知物种的真菌类群。虽然已经很清楚，即使是表面上健康的种子也可能携带潜在的致病真菌，但种子传播的病原体被引入并定植、传播并在新环境中造成影响的可能性仍不清楚，这对评估种子所带来的植物检疫风险提出了挑战。种子贸易。

概括

我们的分析表明，大量的树木种子在国家和大陆之间进行了交易。根据已发表的文献，通过树种移动传播病原真菌的风险很高。然而，与种子相关的分类学和功能多样化的真菌群落的作用仍然知之甚少。特别是，需要更多的研究来评估种子传播的真菌传播到幼苗并在新环境中传播和造成影响的可能性。