Rhizosphere and soil microbiome of apple in replant diseased soil under different management options

Aim of the study was to investigate if different soil management options, including the amendment of catch crops and the inoculation of beneficial microbes, can attentuate the negative plant-soil-feedback induced by continuous replanting of apple (also referred to as apple replant disease). In a greenhouse experiment, we tested five treatments: the pre-culture and amendment of Tagetes patula (Tag) or a catch crop mixture (CCM), or the inoculation of soil/apple plants with beneficial bacteria (Pseudomonas sp. RU47 and Bacillus atrophaeus ABi05, BB), arbuscular mccorhizal fungi (Rhizoglomus irregulare and Funneliformis mossease, AM), and a synthetic community comprising the four abovementioned strains (BB+AM=SynC). Untreated ARD-affected soil served as control (Ctl). Young in vitro propagated apple plants were grown in the differently treated soils for seven weeks. At the end of the experiment, we measured soil macro and micro nutrients, plant growth, root phytoalexins and anylzed the composition of the rhizosphere and root-affected soil microbiome using amplicon sequencing of 16S rRNA gene (V3-V4) and ITS2 region.