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Plants influence numerous soil biotic factors that can alter the performance of later growing plants - defined as plant-soil feedback (PSF). Here, we investigate whether PSF effects are linked with the temporal changes in root exudate diversity and the rhizosphere microbiome of two common grassland species (Holcus lanatus and Jacobaea vulgaris). Both plant species were grown separately establishing conspecific and heterospecific soils. In the feedback phase, we determined plant biomass, measured root exudate composition, and characterized rhizosphere microbial communities weekly (eight time points). Over time, we found a strong negative conspecific PSF on J. vulgaris in its early growth phase which changed into a neutral PSF, whereas H. lanatus exhibited a more persistent negative PSF. Root exudate diversity increased considerably over time for both plant species. Rhizosphere microbial communities were distinct in conspecific and heterospecific soils and showed strong temporal patterns. Bacterial communities converged over time. Using path-models, PSF effects could be linked to the temporal dynamics of root exudate diversity, whereby shifts in rhizosphere microbial diversity contributed to temporal variation in PSF to a lesser extent. Our results highlight the importance of root exudates and rhizosphere microbial communities in driving temporal changes in the strength of PSF effects. This article is protected by copyright. All rights reserved.

Additional figures, including a PRISMA diagram, funnel plots examining publication bias and additional figures showing variation in biomass responses to main effects of warming and drought. The supplementary table shows variation in effect sizes among moderator variables.

Additional file 1: Figure S1. Immunoblot analysis visualizing the expression level of MOA in leave (L) and root (R) crude extracts. The blot was exposed in different timepoints: 1s (A), 10s (B) and 20s (C). FLAG-tagged proteins were detected with anti-FLAG antibodies. (D) Ponceau-S stained immunoblot was used as a blotting control. (E) Coomassie brilliant blue stained SDS-PAGE was used as a loading control. Molecular weights of marker proteins (M) are indicated.

Background Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. Results The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86–91 % and 43–93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18–25 % and 26–35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22–38 %) and survival rate (15–24 %) than those feeding on WT plants. Conclusions The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection., BMC Plant Biology, 21 (1), ISSN:1471-2229

Additional file 3: Figure S2. Plant colonization effects on soil microbial properties. Mean values with confidence intervals of basal respiration [µg O2 g−1 soil dry mass h−1] (a) two and (c) five years, and soil microbial biomass [µg C g−1 soil dry mass] (b) two and (d) five years after colonization by plant species. Circles display basal respiration and soil microbial biomass with resident plant species of weeded subplots, respectively, and open circles display basal respiration and soil microbial biomass with resident plant species plus colonizing plant species of non-weeded subplots, respectively.

Additional file 2: Figure S1. Plant colonization effects on plant cover and plant biomass. Mean values with confidence intervals of colonizing plant species after (a) two years and (b) five years. (c) Mean values with confidence intervals of plant cover [%] after two years and (d) plant biomass [g mâ 2] after five years. In c) and d) circles display plant cover and biomass of resident plant species of weeded subplots, respectively, and open circles display plant cover and biomass with resident plant species plus colonizing plant species of non-weeded subplots, respectively.

Background Several studies have examined the effects of plant colonization on aboveground communities and processes. However, the effects of plant colonization on soil microbial communities are less known. We addressed this gap by studying effects of plant colonization within an experimental plant diversity gradient in subplots that had not been weeded for 2 and 5 years. This study was part of a long-term grassland biodiversity experiment (Jena Experiment) with a gradient in plant species richness (1, 2, 4, 8, 16, and 60 sown species per plot). We measured plant species richness and productivity (aboveground cover and biomass) as well as soil microbial basal respiration and biomass in non-weeded subplots and compared the results with those of weeded subplots of the same plots. Results After 2 and 5 years of plant colonization, the number of colonizing plant species decreased with increasing plant diversity, i.e., low-diversity plant communities were most vulnerable to colonization. Plant colonization offset the significant relationship between sown plant diversity and plant biomass production. In line with plant community responses, soil basal respiration and microbial biomass increased with increasing sown plant diversity in weeded subplots, but soil microbial properties converged in non-weeded subplots and were not significantly affected by the initial plant species richness gradient. Conclusion Colonizing plant species change the quantity and quality of inputs to the soil, thereby altering soil microbial properties. Thus, plant community convergence is likely to be rapidly followed by the convergence of microbial properties in the soil. Electronic supplementary material The online version of this article (doi:10.1186/s12898-016-0073-0) contains supplementary material, which is available to authorized users.