Rhizosphere bacteria and fungi associated with plant growth in soils of three replanted apple orchards.

Background and aims: High-throughput 454 pyrosequencing was applied to investigate differences in bacterial and fungal communities between replant and closely situated control non-replant (fallow) soils. Methods: The V1-V3 region of the bacterial 16S rRNA gene and the ITS1 region of fungi from the different soils were sequenced using 454 pyrosequencing (Titanium chemistry), and data were analysed using the MOTHUR pipeline. Results: The bacterial phyla Proteobacteria, Actinobacteria and Acidobacteria dominated in both fallow and replant apple orchard soils, and community composition at both phylum and genus level did not significantly differ according to NP-MANOVA. The fungal phyla Ascomycota, Zygomycota and Basidiomycota were dominant, and communities also did not differ in composition at either phylum or genus level. High positive Pearson correlations with plant growth in a plant growth assay performed with apple rootstocks plantlets were detected for the bacterial genera Gp16 and Solirubrobacter (r: >0.82) and fungal genera Scutellinia, Penicillium, Lecythophora and Paecilomyces (r: >0.65). Strong negative correlations with plant growth were detected for the bacterial genera Chitinophaga and Hyphomicrobium (r: <−0.78) and the fungal genera Acremonium, Fusarium and Cylindrocarpon (r: <−0.81). Conclusions: Study findings are in part consistent with those of previous research, but also highlight associations between apple plants and certain microbial genera. The functional role of these genera in affecting soil health and fertility should be further investigated. [ABSTRACT FROM AUTHOR]