Fruit function beyond dispersal: effect of fruit decomposition on plant microbiome assembly

Fruits are primarily linked to seed dispersal. However, they might also play a key role in the assembly of the plant microbiome and microbial inheritance. We propose that fruit decomposition directly influences the plant microbiome and plant fitness. Additionally, we hypothesized that fruit decomposition alters the microbiomes of soil and seedlings. We used amplicon sequencing to analyse microbial communities associated with the soil, rhizosphere, and phyllosphere of tomato and chili plants grown with and without their fruit. We demonstrated that fruit decomposition decreased the germination rate and phyllosphere microbial diversity, and influenced the phyllosphere and rhizosphere community composition. Moreover, fruit decomposition increased soil microbial diversity and drastically altered microbial community composition as well as predicted microbial functions. Soil physiochemical properties were influenced by fruit decomposition, resulting in high organic carbon accumulation and distinct availability of crucial elements such as sulfur, magnesium, and potassium. The phyllosphere and rhizosphere microbiomes showed differences, with fruit and seed treatments driving unique microbial enrichments in each compartment, which subsequently resulted in distinct predicted functions. This study provides evidence that fruits may have an alternative function beyond seed dispersal in plant microbial assembly and microbial inheritance, potentially shaping the development and success of plant offspring.果实主要与种子传播相关。然而，它们或许在植物微生物组（plant microbiome）的组装与微生物遗传过程中也发挥关键作用。我们提出，果实腐烂会直接影响植物微生物组与植物适合度。此外，我们假设果实腐烂会改变土壤与幼苗的微生物组。我们借助扩增子测序（amplicon sequencing）技术，分析了有无果实的番茄与辣椒植株的土壤、根际（rhizosphere）及叶际（phyllosphere）相关微生物群落。研究结果表明，果实腐烂会降低种子发芽率与叶际微生物多样性，并影响叶际和根际的群落组成。此外，果实腐烂会提升土壤微生物多样性，显著改变微生物群落组成及预测的微生物功能。果实腐烂会影响土壤理化性质（soil physiochemical properties），导致有机碳（organic carbon）大量积累，同时使硫、镁、钾等关键元素的有效性发生显著变化。叶际与根际微生物组存在差异，果实与种子处理会在各微生境中驱动独特的微生物富集，进而产生不同的预测功能。本研究提供了证据，表明果实或许在种子传播之外，还存在植物微生物组装与微生物遗传层面的其他功能，或可塑造植物后代的发育与存活成功率。