Seed microbiota acts as a starting point for the assembly of the plant microbiota and contributes to successful plant establishment. To date, the order and timing of microbial taxa immigration during seed development and maturation remained unknown. We investigated the temporal dynamics of seed bacterial communities in bean and radish. A high phylogenetic turnover was observed for both plant species with few taxa associated with all seed developmental stages. Greater heterogeneity in community structure within each stage was observed for radish. While about one-third of radish seed bacterial taxa were detected in buds, flowers and fruits, very few taxa seem to be transmitted by the floral route in bean. In the latter species, bacterial populations belonging to the P. fluorescens species complex were found either in buds, flowers and fruits or in seeds. The relative phylogenetic proximity of these bacterial populations combined with their habitat specificity led us to explore the genetic determinants involved in successful seed transmission in bean. Comparative genomic analyses of representatives bacterial strains revealed dozens of coding sequences specifically associated with seed-transmitted strains. This study provided a first glimpse on processes involved in seed microbiota assembly, which could be used for designing plant-beneficial microbial consortia.

中文翻译：

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种子发育和成熟过程中细菌群落的时间动态。

种子微生物群是植物微生物群组装的起点，有助于植物成功建立。迄今为止，种子发育和成熟过程中微生物类群迁移的顺序和时间仍然未知。我们调查了豆类和萝卜种子细菌群落的时间动态。对于与所有种子发育阶段相关的几乎没有分类群的两种植物物种，都观察到了高系统发育周转。对于萝卜，观察到每个阶段内群落结构的异质性更大。虽然大约三分之一的萝卜种子细菌分类群是在芽、花和果实中检测到的，但似乎很少有分类群通过豆类的花途径传播。在后一种物种中，属于荧光假单胞菌的细菌种群在芽、花和果实中或在种子中发现了物种复合体。这些细菌种群的相对系统发育接近性以及它们的栖息地特异性使我们探索了与豆类种子成功传播有关的遗传决定因素。代表性细菌菌株的比较基因组分析揭示了数十个与种子传播菌株特别相关的编码序列。这项研究首次了解了种子微生物群组装过程，可用于设计对植物有益的微生物群落。