PDF(Pubmed)
Abstract：
Modulating the soil microbiome by applying microbial inoculants has gained increasing attention as eco-friendly option to improve soil disease suppressiveness. Currently, studies unraveling the interplay of inoculants, root-associated microbiome, and plant response are lacking for apple trees. Here, we provide insights into the ability of Bacillus velezensis FZB42 or Pseudomonas sp. RU47 to colonize apple root-associated microhabitats and to modulate their microbiome. We applied the two strains to apple plants grown in soils from the same site either affected by apple replant disease (ARD) or not (grass), screened their establishment by selective plating, and measured phytoalexins in roots 3, 16, and 28 days post inoculation (dpi). Sequencing of 16S rRNA gene and ITS fragments amplified from DNA extracted 28 dpi from different microhabitat samples revealed significant inoculation effects on fungal β-diversity in root-affected soil and rhizoplane. Interestingly, only in ARD soil, most abundant bacterial amplicon sequence variants (ASVs) changed significantly in relative abundance. Relative abundances of ASVs affiliated with Enterobacteriaceae were higher in rhizoplane of apple grown in ARD soil and reduced by both inoculants. Bacterial communities in the root endosphere were not affected by the inoculants but their presence was indicated. Interestingly and previously unobserved, apple plants responded to the inoculants with increased phytoalexin content in roots, more pronounced in grass than ARD soil. Altogether, our results indicate that FZB42 and RU47 were rhizosphere competent, modulated the root-associated microbiome, and were perceived by the apple plants, which could make them interesting candidates for an eco-friendly mitigation strategy of ARD. KEY POINTS: • Rhizosphere competent inoculants modulated the microbiome (mainly fungi) • Inoculants reduced relative abundance of Enterobacteriaceae in the ARD rhizoplane • Inoculants increased phytoalexin content in roots, stronger in grass than ARD soil.
摘要：
通过施用微生物接种剂调节土壤微生物组作为改善土壤病害抑制性的生态友好选择越来越受到关注。目前,研究揭示了接种剂的相互作用，根相关微生物组，苹果树缺乏植物反应。这里,我们提供了有关Velezensis芽孢杆菌FZB42或假单胞菌的能力的见解。RU47定殖苹果根相关微生境并调节其微生物组。我们将这两种菌株应用于在同一地点的土壤中生长的苹果植物，无论是受苹果再植病（ARD）还是不受（草）的影响，通过选择性电镀筛选他们的机构，并在接种后3、16和28天(dpi)测量根中的植物抗毒素。从不同微生境样品中提取的28dpi的DNA中扩增的16SrRNA基因和ITS片段的测序显示，在受影响的土壤和根际平面中，接种对真菌β多样性的显着影响。有趣的是,仅在ARD土壤中，最丰富的细菌扩增子序列变体（ASV）的相对丰度显着变化。在ARD土壤中生长的苹果的根际平面中，与肠杆菌科相关的ASV的相对丰度较高，而两种接种剂都降低了。根内皮层中的细菌群落不受接种剂的影响，但表明它们的存在。有趣的是，以前没有观察到，苹果植物对接种剂的反应是根中植物抗毒素含量增加，在草地上比在ARD土壤中更明显。总之,我们的结果表明，FZB42和RU47具有根际能力，调节根相关的微生物组，被苹果植物感知，这可能使他们成为ARD生态友好型缓解战略的有趣候选人。关键点：•根际活性接种物调节微生物组（主要是真菌）•接种物降低了ARD根际平面中肠杆菌科的相对丰度•接种物增加了根中的植物抗毒素含量，在草地上比ARD土壤更强。
