Browsing by Person "Babin, Doreen"

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Beneficial microbial consortium improves winter rye performance by modulating bacterial communities in the rhizosphere and enhancing plant nutrient acquisition
(2023) Behr, Jan Helge; Kampouris, Ioannis D.; Babin, Doreen; Sommermann, Loreen; Francioli, Davide; Kuhl-Nagel, Theresa; Chowdhury, Soumitra Paul; Geistlinger, Joerg; Smalla, Kornelia; Neumann, Günter; Grosch, Rita
The beneficial effect of microbial consortium application on plants is strongly affected by soil conditions, which are influenced by farming practices. The establishment of microbial inoculants in the rhizosphere is a prerequisite for successful plant-microorganism interactions. This study investigated whether a consortium of beneficial microorganisms establishes in the rhizosphere of a winter crop during the vegetation period, including the winter growing season. In addition, we aimed for a better understanding of its effect on plant performance under different farming practices. Winter rye plants grown in a long-time field trial under conventional or organic farming practices were inoculated after plant emergence in autumn with a microbial consortium containing Pseudomonas sp. (RU47), Bacillus atrophaeus (ABi03) and Trichoderma harzianum (OMG16). The density of the microbial inoculants in the rhizosphere and root-associated soil was quantified in autumn and the following spring. Furthermore, the influence of the consortium on plant performance and on the rhizosphere bacterial community assembly was investigated using a multidisciplinary approach. Selective plating showed a high colonization density of individual microorganisms of the consortium in the rhizosphere and root-associated soil of winter rye throughout its early growth cycle. 16S rRNA gene amplicon sequencing showed that the farming practice affected mainly the rhizosphere bacterial communities in autumn and spring. However, the microbial consortium inoculated altered also the bacterial community composition at each sampling time point, especially at the beginning of the new growing season in spring. Inoculation of winter rye with the microbial consortium significantly improved the plant nutrient status and performance especially under organic farming. In summary, the microbial consortium showed sufficient efficacy throughout vegetation dormancy when inoculated in autumn and contributed to better plant performance, indicating the potential of microbe-based solutions in organic farming where nutrient availability is limited.
Effect of long-term agricultural management on the soil microbiota influenced by the time of soil sampling
(2022) Fernandez-Gnecco, Gabriela; Covacevich, Fernanda; Consolo, Veronica F.; Behr, Jan H.; Sommermann, Loreen; Moradtalab, Narges; Maccario, Lorrie; Sørensen, Søren J.; Deubel, Annette; Schellenberg, Ingo; Geistlinger, Joerg; Neumann, Günter; Grosch, Rita; Smalla, Kornelia; Babin, Doreen
Application of agrochemicals and mechanization enabled increasing agricultural productivity yet caused various environmental and soil health-related problems. Agricultural practices affect soil microorganisms, which are the key players of many ecosystem processes. However, less is known about whether this effect differs between time points. Therefore, soil was sampled in winter (without crop) and in summer (in the presence of maize) from a long-term field experiment (LTE) in Bernburg (Germany) managed either under cultivator tillage (CT) or moldboard plow (MP) in combination with either intensive nitrogen (N)-fertilization and pesticides (Int) or extensive reduced N-fertilization without fungicides (Ext), respectively. High-throughput sequencing of 16S rRNA gene and fungal ITS2 amplicons showed that changes in the microbial community composition were correlated to differences in soil chemical properties caused by tillage practice. Microbial communities of soils sampled in winter differed only depending on the tillage practice while, in summer, also a strong effect of the fertilization intensity was observed. A small proportion of microbial taxa was shared between soils from the two sampling times, suggesting the existence of a stable core microbiota at the LTE. In general, taxa associated with organic matter decomposition (such as Actinobacteria, Bacteroidetes, Rhizopus, and Exophiala) had a higher relative abundance under CT. Among the taxa with significant changes in relative abundances due to different long-term agricultural practices were putative pathogenic (e.g., Gibellulopsis and Gibberella) and beneficial microbial genera (e.g., Chitinophagaceae, Ferruginibacter, and Minimedusa). In summary, this study suggests that the effects of long-term agricultural management practices on the soil microbiota are influenced by the soil sampling time, and this needs to be kept in mind in future studies for the interpretation of field data.
Long-term fertilization strategy impacts rhizoctonia solani-microbe interactions in soil and rhizosphere and defense responses in lettuce
(2022) Sommermann, Loreen; Babin, Doreen; Behr, Jan Helge; Chowdhury, Soumitra Paul; Sandmann, Martin; Windisch, Saskia; Neumann, Günter; Nesme, Joseph; Sørensen, Søren J.; Schellenberg, Ingo; Rothballer, Michael; Geistlinger, Joerg; Smalla, Kornelia; Grosch, Rita
The long-term effects of agricultural management such as different fertilization strategies on soil microbiota and soil suppressiveness against plant pathogens are crucial. Therefore, the suppressiveness of soils differing in fertilization history was assessed using two Rhizoctonia solani isolates and their respective host plants (lettuce, sugar beet) in pot experiments. Further, the effects of fertilization history and the pathogen R. solani AG1-IB on the bulk soil, root-associated soil and rhizosphere microbiota of lettuce were analyzed based on amplicon sequencing of the 16S rRNA gene and ITS2 region. Organic fertilization history supported the spread of the soil-borne pathogens compared to long-term mineral fertilization. The fertilization strategy affected bacterial and fungal community composition in the root-associated soil and rhizosphere, respectively, but only the fungal community shifted in response to the inoculated pathogen. The potential plant-beneficial genus Talaromyces was enriched in the rhizosphere by organic fertilization and presence of the pathogen. Moreover, increased expression levels of defense-related genes in shoots of lettuce were observed in the soil with organic fertilization history, both in the absence and presence of the pathogen. This may reflect the enrichment of potential plant-beneficial microorganisms in the rhizosphere, but also pathogen infestation. However, enhanced defense responses resulted in retarded plant growth in the presence of R. solani (plant growth/defense tradeoff).