Species within the Caulobacter genus have been termed ‘hub species’ in the plant microbiome. To understand these interactions, we assessed the interactions between several Caulobacter strains and a common host plant. We identified a set of 11 Caulobacter strains that range in genetic diversity and tested them for their ability to increase the growth of Arabidopsis thaliana. In addition, biochemical assays were employed to determine if these Caulobacter strains produce common plant growth promoting (PGP) biosynthates. To identify potential PGP-related genes, genomic analyses were performed to compare the genomes of PGP Caulobacter strains to those of non-PGP Caulobacter strains. For the PGP Caulobacter strains, we observed that common PGP biosynthates did not contribute to the observed Caulobacter-mediated plant growth stimulation. Genomic analyses suggested that the genomes of PGP strains maintain similar metabolic pathways compared to those of non-PGP strains, and that common genes related to PGP factors do not explain the PGP mechanisms for the Caulobacter strains we analyzed. Plant growth enhancement is not a conserved feature in the Caulobacter genus, and some Caulobacter strains even inhibit plant growth. Moreover, common PGP factors do not fully explain Caulobacter-mediated plant growth enhancement.

中文翻译：

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植物生长增强不是 Caulobacter 属的保守特征

Caulobacter 属内的物种在植物微生物组中被称为“枢纽物种”。为了理解这些相互作用，我们评估了几种 Caulobacter 菌株和一种常见宿主植物之间的相互作用。我们确定了一组 11 种具有遗传多样性的 Caulobacter 菌株，并测试了它们促进拟南芥生长的能力。此外，还采用生化分析来确定这些 Caulobacter 菌株是否产生常见的植物生长促进 (PGP) 生物合成物。为了鉴定潜在的 PGP 相关基因，进行了基因组分析以比较 PGP 茎杆菌菌株与非 PGP 茎杆菌菌株的基因组。对于 PGP Caulobacter 菌株，我们观察到常见的 PGP 生物合成物对观察到的 Caulobacter 介导的植物生长刺激没有贡献。基因组分析表明，与非 PGP 菌株相比，PGP 菌株的基因组保持相似的代谢途径，并且与 PGP 因子相关的常见基因不能解释我们分析的 Caulobacter 菌株的 PGP 机制。植物生长增强不是 Caulobacter 属的保守特征，一些 Caulobacter 菌株甚至抑制植物生长。此外，常见的 PGP 因子并不能完全解释 Caulobacter 介导的植物生长增强。