Data underlying the publication: Beetroot and Spinach Seed Microbiomes Can Suppress Pythium ultimum Infection; Results from a Large-Scale Screening

Seed health is an indispensable prerequisite of food security. While the toolkit of plant protection products is currently limited, evidence suggests that the seed microbiome could protect seeds from pathogens. Thus, given their possible disease suppressive potential, we tested 11 different pathosystems to achieve the following proof-of-concept: seed microbiomes can be beneficial for seed health through conferring disease suppression. This study focused on beetroot, onion, spinach, pepper, coriander, red fescue and perennial ryegrass seeds, with each crop being challenged with one or two from a total of six pathogens, namely <em>Pythium ultimum</em> (or a <em>Pythium</em> sp.), <em>Setophoma terrestris</em>, <em>Fusarium</em> <em>oxysporum</em>, <em>Phytophthora</em> <em>capsici</em>, <em>Laetisaria</em> <em>fuciformis</em> and a mix of <em>Puccinia</em> sp. isolates. Each seed lot of each crop was tested with and without treatment with a disinfectant as a proxy for comparing intact seed microbiomes with seed microbiomes after partial elimination by disinfection. We found disease suppression in two pathosystems. Beetroot and spinach seed lots were able to suppress disease caused by <em>P. ultimum </em>when their microbiomes were intact but not after seed disinfection. We speculate that this relates to the microorganisms residing on and in the seed. Yet, seed microbiome disease suppression was not found in all pathosystems, highlighting the variation in seed morphology, plant cultivars, pathogens and seed disinfection treatments. A holistic understanding of the characteristics of seeds that harbour suppressive microbiomes as well as the pathogens that are sensitive to suppression, could lead to more targeted and informed seed processing and treatment and, consequently, to the sustainable management of seedling diseases.

种子健康是粮食安全不可或缺的前提条件。尽管当前可用的植物保护药剂种类仍较为有限，但已有研究表明种子微生物组（seed microbiome）可帮助种子抵御病原菌。鉴于其潜在的病害抑制能力，本研究针对11种不同的病害体系（pathosystem）开展试验，以完成如下概念验证：种子微生物组可通过赋予病害抑制能力，助力种子健康。本研究聚焦于甜菜根、洋葱、菠菜、辣椒、芫荽、紫羊茅和多年生黑麦草的种子，每种作物分别接种共计6种病原菌中的1种或2种，即终极腐霉（*Pythium ultimum*，或腐霉属（*Pythium* sp.）菌株）、*Setophoma terrestris*、尖孢镰刀菌（*Fusarium oxysporum*）、辣椒疫霉（*Phytophthora capsici*）、*Laetisaria fuciformis*以及柄锈菌属（*Puccinia* sp.）分离菌株混合菌群。本研究对每种作物的每批种子均设置消毒与未消毒两组处理，以此作为对照，比较完整种子微生物组与经消毒部分去除微生物后的种子微生物组的差异。本研究在2种病害体系中观测到了病害抑制现象。甜菜根与菠菜种子批次在微生物组完整的情况下，能够抑制由终极腐霉（*P. ultimum*）引发的病害，但经种子消毒后则丧失该能力。我们推测该现象与种子表面及内部定殖的微生物相关。但并非所有病害体系中均观测到种子微生物组的病害抑制效应，这凸显了种子形态、植物品种、病原菌以及种子消毒处理方式之间的差异。若能全面解析携带具有病害抑制能力的微生物组的种子特性，以及对抑制作用敏感的病原菌特性，将有助于制定更具针对性且科学合理的种子加工与处理方案，进而实现幼苗病害的可持续防控。