Abstract
The targeted application of plant growth-promoting rhizobacteria (PGPR) provides the key for a future sustainable agriculture with reduced pesticide application. PGPR interaction with the indigenous microbiota is poorly understood, but essential to develop reliable applications. Therefore, Stenotrophomonas rhizophila SPA-P69 was applied as a seed coating and in combination with a fungicide based on the active ingredients fludioxonil, metalaxyl-M, captan and ziram. The plant performances and rhizosphere compositions of treated and non-treated maize plants of two field trials were analyzed. Plant health was significantly increased by treatment; however, overall corn yield was not changed. By applying high-throughput amplicon sequencing of the 16S rRNA and the ITS genes, the bacterial and fungal changes in the rhizosphere due to different treatments were determined. Despite the fact that treatments had a significant impact on the rhizosphere microbiota (9–12%), the field site was identified as the main driver (27–37%). The soil microbiota composition from each site was significantly different, which explains the site-specific effects. In this study we were able to show the first indications how PGPR treatments increase plant health via microbiome shifts in a site-specific manner. This way, first steps towards a detailed understanding of PGPRs and developments of consistently efficient applications in diverse environments are made.
Highlights
Plants live in close interaction with microorganisms and are recognized as holobionts [1]
To understand the interaction between plant growth-promoting rhizobacteria (PGPR) and the indigenous microbiota under field conditions, we studied the effect of the interaction of the maize rhizosphere microbiome and the PGPR Stenotrophomonas rhizophila Stress Protecting Agent (SPA)-P69 on maize as a model plant [21]
We evaluated the agronomic parameter (I), strain establishment in the rhizosphere (II), and looked at the global impact of the treatments using different field sites (III)
Summary
Plants live in close interaction with microorganisms and are recognized as holobionts [1]. This close coevolution developed mainly mutualistic, commensal and neutral, and pathogenic, interactions [2,3,4]. Beneficial plant–microbe interactions in the rhizosphere were found to be very important throughout the plant’s lifecycle [5]. World-wide, farmers are increasingly specialized in the production of distinct crops based on intensive management practice. This has consequences for soil-borne pathogens because they accumulate in soil and enhance disease pressure on crops over time [9]
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