The Brassica napus seed microbiota is cultivar-specific and transmitted via paternal breeding lines. Oilseed rape seed microbiota

Seed microbiota influence germination and plant health and have the potential to improve crop performance, but the factors that determine their structure and functions are still not fully understood. Here, we analyzed the impact of plant-related and external factors on seed endophyte communities of ten different oilseed rape (Brassica napus L.) cultivars from 26 field sites across Europe. All seed lots harbored a high abundance and diversity of endophytes, consisting of 265 bacterial ASVs on average, which were dominated by six genera: Ralstonia, Serratia, Enterobacter, Pseudomonas, Pantoea, and Sphingomonas. The cultivar was the main factor explaining the variations in bacterial diversity, abundance, and composition. In addition, the latter was significantly influenced by diverse biotic and abiotic factors, e.g. host germination rates and disease resistance against Plasmodiophora brassicae. A set of bacterial biomarkers was identified to discriminate between characteristics of the seeds, e.g. Sphingomonas for improved germination and Brevundimonas for diseases resistance. Application of a Bayesian community approach suggested vertical transmission of seed endophytes, where the paternal parent plays a major role and might even determine the germination performance of the offspring. This study contributes to the understanding of seed microbiome assembly and underlines the potential of the microbiome to be implemented in crop breeding and biocontrol programs.

种子微生物群（seed microbiota）可影响种子萌发与植物健康，具备提升作物表现的潜力，但目前学界尚未完全阐明决定其群落结构与功能的调控因素。本研究针对欧洲26个田间试验点的10个不同油菜（Brassica napus L.）品种的种子内生菌群，分析了植物相关及外部因素对其的影响。所有种子批次均携带丰富且多样的内生菌，平均包含265个细菌扩增子序列变异体（amplicon sequence variants，ASVs），优势类群涵盖6个菌属：罗尔斯通氏菌属（Ralstonia）、沙雷氏菌属（Serratia）、肠杆菌属（Enterobacter）、假单胞菌属（Pseudomonas）、泛菌属（Pantoea）以及鞘氨醇单胞菌属（Sphingomonas）。品种是解释细菌多样性、丰度与群落组成差异的核心驱动因子。此外，群落组成还受到多种生物与非生物因素的显著影响，例如宿主种子萌发率以及对芸薹根肿菌（Plasmodiophora brassicae）的抗病性。研究团队鉴定出一组可区分种子特性的细菌生物标志物：其中鞘氨醇单胞菌属与种子萌发性能提升相关，短波单胞菌属（Brevundimonas）则与病害抗性相关。通过贝叶斯群落分析方法，本研究证实种子内生菌存在垂直传递现象，其中父本发挥主要调控作用，甚至可决定子代的萌发性能。本研究增进了学界对种子微生物组组装机制的理解，并强调了微生物组在作物育种与生物防治项目中的应用潜力。