Biology subjects

Kuramae, E. E.

Publications and source records attributed to Kuramae, E. E..

4 recordsLinked to original sources

bioRxiv2024

Unveiling the dominant role of soil pH in shaping nitrogen cycling microbial gene abundances: Insights from 65-years of chemical fertilizer selection in acidic grassland meadow

Understanding the microbial processes driving the nitrogen (N) cycle is crucial for enhancing plant productivity and mitigating environmental pollution. The long-term application of synthetic fertilizers induces significant alterations in the microbial community functions. Microbes inhabiting acidic soils may exhibit distinct responses to chemical fertilizer application compared to soils with neutral pH. However, the chronic or occasional changes resulting from repeated nutrient flushes due to fertilizer application remain insufficiently elucidated, especially in acidic grasslands. Therefore, our study was on an acidic semi-natural grassland, where the soil was subjected to chemical fertilizer P (superphosphate), K (potassium sulfate), PK, N (ammonium nitrate), NPK, PK+N (PK applied in spring and N applied once in summer) over a span of 65 years. Gene abundances associated with the N-cycle (amoA, nifH, nirK, nirS, and nosZ) were quantified at seven different time points throughout the year considering the temporal effect caused by fertilizer application. Our findings reveal that in the long term, soil pH emerged as the predominant factor influencing the gene abundance related to N-fixation and denitrification outweighing the impact of nutrient availability. Notably, the application of N fertilizer had a positive effect on the abundance of nitrifiers, while the abundance of denitrifiers decreased due to soil acidification induced by fertilizer application. In summary, our study highlights that the microbial community involved in N cycling is more sensitive to the difference in soil pH shaped by long-term fertilizer application rather than to the direct impact of fertilizer application. HighlightO_LISeasonal sampling confirmed the long-term effect of fertilizer on microbial N-cycling genes C_LIO_LIFertilizer types shaped soil pH, consequently impacted on diazotrophs and denitrifies abundances C_LIO_LIAbundance of denitrifying microbe did not explain the increase of N2O emission by N fertilizer C_LIO_LIN2O emission was positively correlated with AOA abundance C_LI

microbiology↗

bioRxiv2024

Liming enhances the abundance and stability of nitrogen-cycling microbes: The buffering effect of long-term lime application

Lime application (liming) has historically been used to ameliorate soil acidity in grasslands. Liming effectively improves soil pH, plant productivity, and soil physicochemical properties, but the long-term impact of acidity control by liming on key microbial nitrogen (N)-cycling genes in semi-natural grasslands is unknown. We investigated the effect of 65 years of liming on N-cycling processes in the limed and control plots of the Ossekampen long-term grassland experiment in the Netherlands. These plots have not received any other fertilizers for 65 years. Soil sampling and nitrous oxide (N2O) emission measurements were conducted three times in spring and four times in summer, and quantitative real-time PCR was performed to determine the abundances of N-cycling genes, including ammonia-oxidation (amoA), denitrification (nirS, nirK, nosZ), and N-fixation (nifH) genes. Long-term liming increased the abundances of nitrifiers and denitrifiers but did not increase N2O emissions. Additionally, liming had a buffering effect that stabilized the population of N-cycling microbes against seasonal variations in abundance. Our results indicate that improving soil acidity through liming facilitates microbial N-cycling processes without increasing N2O emissions. HighlightsO_LI65 years of liming increased bacterial but not archaeal and fungal community abundance. C_LIO_LILiming increased the abundance of microbial N-cycling genes. C_LIO_LIThe buffering effect of liming reduced seasonal variations in the abundance of N microbes. C_LI

microbiology↗

bioRxiv2023

Reciprocal interactions between the sorghum root microbiome and the parasitic weed Striga hermonthica

The soil microbiome plays a crucial role in protecting plants against various pests and pathogens. However, its impact on interactions between plants and parasitic weeds, such as Striga hermonthica, is poorly understood. In this study, sorghum plants susceptible to Striga were grown in 22 different field soils infested with parasite seeds. Significant variations in Striga infections were observed among the soils. When the most Striga-suppressive soil was gamma-irradiated, there was a significant increase in Striga attachments, highlighting the importance of the soil microbiome in disrupting parasite infection. In the presence of the soil microbiome, the Striga-susceptible sorghum plants performed similarly to three Striga-resistant genotypes. This effect was lost when the soil microbiome was eliminated by gamma-irradiation. Subsequent analysis revealed that Striga substantially affected the sorghum rhizosphere microbiome and that both the sorghum rhizosphere mycobiome and bacteriome composition significantly correlated with Striga attachment. Interestingly, certain fungal species in the sorghum rhizosphere mycobiome were only detected when Striga seeds were present. Further investigation showed that these fungal taxa originated from the Striga seeds and are known sorghum pathogens, suggesting a potential partnership between Striga and fungal pathogens to invade their shared host. Overall, our study demonstrated that the soil microbiome influences Striga infection and sorghum performance in a genotype-dependent manner, and the microbiome of Striga seeds affects the composition of the sorghum rhizosphere microbiome.

ecology↗

bioRxiv2022

The soil microbiome reduces Striga infection of sorghum by modulation of host-derived signaling molecules and root development

Sorghum bicolor is one of the most important cereals in the world and a staple crop for smallholder famers in sub-Saharan Africa. However approximately 20% of sorghum yield is annually lost on the African continent due to infestation with the root parasitic weed Striga hermonthica. Existing Striga management strategies often show an inconsistent to low efficacy. Hence, novel and integrated approaches are needed as an alternative strategy. Here, we demonstrate that the soil microbiome suppresses Striga infection in sorghum. We associate this suppression with microbiome-mediated induction of root endodermal suberization and aerenchyma formation, and depletion of haustorium inducing factors (HIFs), root exudate compounds that are critical for the initial stages of Striga infection. We further identify microbial taxa associated with reduced Striga infection with concomitant changes in root cellular anatomy and differentiation as well as HIF degradation. Our study describes novel microbiome-mediated mechanisms of Striga suppression, encompassing repression of haustorium formation and induction of physical barriers in the host root tissue. These findings open new avenues to broaden the effectiveness of Striga management practices.

plant biology↗