The effects of plant type, AMF inoculation and water regime on rhizosphere microbial communities

Abstract

Different plant species, water regimes and microbes in the rhizosphere might shape rhizosphere microbial communities due to their effects on root exudation patterns and interactions. In this study, we investigated whether rhizosphere microbial communities have distinct structures according to plant type (Festuca pratensis, Dactylis glomerata or a mixture of both species), water regime (dry and wet pots) and inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis (AMF). Following a 60‐day pot experiment we assessed the rhizosphere microbial population structure via phospholipid fatty acids (PLFAs) and soil processes via the activity of N‐acetyl‐glucosaminidase (NAG), acid phosphatase and urease, and inorganic nitrogen (N) and phosphorus (P). Higher AMF colonization was recorded in F. pratensis, although its root and shoot biomass was lower than in D. glomerata. Although growth differed between the plant types, this exerted no influence on rhizosphere microbial biomass. Low water content decreased the biomass of all microbial groups, whereas inoculation with AMF decreased the biomass of fungi and increased that of bacteria. For enzyme activities only urease showed a response to treatments. Arbuscular mycorrhizal fungi inoculation increased available P and shifted mineral N content from nitrate to ammonium. The water regime had a dominant effect on the structure of the microbial communities, suggesting a direct effect of water on microbes. In wet soils, the structure of the microbial communities was modulated mainly by inoculation; AMF‐inoculated D. glomerata soils showed distinct communities. In dry soils, plant type exerted a profound effect on rhizosphere communities; the communities of all three plant types differed, probably due to limitations in the diffusion of nutrients or via reduced root exudation. We concluded that the relative importance of factors shaping rhizosphere microbial communities varies depending on soil moisture regime. Highlights Microbial communities were studied in relation to water regime, plant species and AMF inoculation In wet soils, the microbial communities of AMF‐inoculated D. glomerata plants differed from other communities In dry soils, the microbial communities of D. glomerata and mixtures differed AMF increased bacterial biomass and soil P but decreased nitrate:ammonium ratio

Effect of Different Combinations of Phosphorus and Nitrogen Fertilization on Arbuscular Mycorrhizal Fungi and Aphids in Wheat

“…Additionally, reducing P results in a high AMF colonization rate of plant roots [86], which can improve photosynthesis [87], these reports are also proved by our results, especially in the common garden experiments. There was no significant effect of P on the AMF colonization in field trial, which may be due to the heavy rain in this year, because previous report suggests that the mean colonization rate in wet soils is lower than dry soils by 35.29% [88]. Regardless, these findings are line with the SEM results, which showed a negative relationship between the amount of P and AMF and a positive relationship between AMF and the concentrations of total phenolics and flavonoids.…”

The Aromatic Plant Clary Sage Shaped Bacterial Communities in the Roots and in the Trace Element-Contaminated Soil More Than Mycorrhizal Inoculation – A Two-Year Monitoring Field Trial

“…Surprisingly, AMF inoculation, which is likely to result in a shift of the bacterial communities in soil and in root of the cultivated plants did not lead to tremendous changes in our experimental conditions (Lioussanne et al, 2010;Rodríguez-Caballero et al, 2017;Akyol et al, 2019;Monokrousos et al, 2019). No significance of AMF inoculation either in the PERMANOVA analysis or in the Venn diagram representation was observed, with a high number of shared ASVs between inoculated and non-inoculated treatments, whatever the biotope and the year of sampling.…”

“…This could be responsible for the relatively low abundance of Acidobacteria and Proteobacteria observed in our conditions. As soil microbial community structure is driven by dominant sources of bioavailable C, plant species is then another determinant factor (Köberl et al, 2013;Monokrousos et al, 2019;Wang et al, 2019). In particular, plants are able to secrete specific root exudates and to modulate their nature (sugars, sterols, amino and organic acids), hence shaping the microbial communities' structure accordingly in the rhizosphere (Wang X. et al, 2018;Misra et al, 2019).…”

“…It is believed that the distinctive microbiome around aromatic plants is highly specific and dependant on the plant species and on the related nature and abundance of secondary metabolites, present in the root exudates (Köberl et al, 2013;Adamovic et al, 2015;Misra et al, 2019). Apart from the effects of plant's driven changes on microbial communities, it has been previously reported that mycorrhizal inoculation can also influence the microbial community structure (Lioussanne et al, 2010;Akyol et al, 2019;Monokrousos et al, 2019;Dagher et al, 2020a). Soil bacteria may obtain carbon from AMF hyphae exudates or use the hyphae themselves as substrate (Qin et al, 2016;Gui et al, 2017), creating a niche for the growth of specific bacteria (Toljander et al, 2006;Gui et al, 2017).…”

Study on The Influence of Direct Ground Liquid CO2 Injection on Soil Chemical Properties in Subsidence Areas under Shallow Buried Geological Conditions

“…Wang et al studied the changes in soil nutrient content in the collapsed area and noncollapsed area and 17 years after the collapse and concluded that the soil nutrient can only gradually recover 12 to 17 years after the collapse [3]. Monokrousos et al studied the variation of the chemical properties of soil organic matter, organic nitrogen, and available phosphorus at the deposition site after mining over time and concluded that the content of these nutrient elements gradually increased over time [9]. Zhao et al used the surface soil (0∼60 cm) in the coal mining subsidence area of Daliuta as the research object, using traditional statistical methods to study the vertical variability of soil water content and using the kriging local interpolation method in geostatistics to study the planar variability of soil moisture content [10].…”