Pedosphere最新文献

Potential changes in the symbiotic relationship between rice (Oryza sativa) and microorganisms have occurred during the domestication of Asian cultivated rice (O. sativa) from common wild rice (Oryza rufipogon) and in response to global climate change, along with evolving adaptations to the environment. The potential genes may express differently or dominate the symbiotic relationships between arbuscular mycorrhizal fungi (AMF) and plants, which may be beneficial to rice breeding. To date, research on this important topic has been limited. In this study, we aimed to examine the symbiotic relationships of Asian common wild and cultivated rice species with AMF. By conducting a comparative metagenomic analysis of the rhizospheres of wild and cultivated rice species, we identified differences in Rhizophagus intraradices-related genes associated with wild and cultivated rice, as well as functional genes of AMF. Furthermore, we obtained root-related genes associated with AMF from transcriptome data of rice roots. Our results collectively suggest that R. intraradices-related genes in the rhizosphere of wild rice may be more conducive to its colonization. Additionally, bacteria from the Nitrosomonadaceae and Nitrospiraceae families identified in the rhizosphere of wild rice exhibited positive correlations with R. intraradices-related genes with protein identifiers 1480749 and 1871253, which may indicate that nitrobacteria can enhance the functions of R. intraradices in association with wild rice. Next, in a case study using comparative transcriptome analysis of root samples obtained from R. intraradices-inoculated wild and cultivated rice plants, we found significantly higher expression levels of the strigolactone pathway-related genes DWARF3 (D3) and DWARF14 (D14) in R. intraradices-inoculated common wild rice than in R. intraradices-inoculated cultivated rice. This study provides a theoretical basis for identifying the effects of domestication on mycorrhizal symbiosis-related genes, which could be promoted in wild rice in the future.},

Straw return can be used to reduce fertilizer input and improve agricultural sustainability and soil health. However, how straw return and reduced fertilizer application affect beneficial soil microbes, particularly arbuscular mycorrhizal fungi (AMF), remains poorly understood. Here, we conducted a five-year field experiment in a rainfed maize field on the Loess Plateau of northwestern China. We tested four treatments with straw return combined with four nitrogen (N) application rates, i.e., 100%, 80%, 60%, and 0% of the common N application rate (225 kg N ha^-1 year^-1) in this region, and two reference treatments (full or no N application), with three replicates for each treatment. Mycorrhizal colonization was quantified and AMF communities colonizing maize roots were characterized using Illumina sequencing. Forty virtual taxa (VTs) of AMF were identified in root samples, among which VT113 (related to Rhizophagus fasciculatus) and VT156 (related to Dominikia gansuensis) were the predominant taxa. Both root length colonization and AMF VT richness were sensitive to N fertilization, but not to straw return; furthermore, both gradually increased with decreasing N application rate. The VT composition of the AMF community was also affected by N fertilization, but not by straw return, and the community variation could be well explained by soil available N and phosphorus concentrations. Additionally, 60%, 80%, and full N fertilization produced similar maize yields. Thus, our study revealed the response patterns of AMF to straw return and N fertilizer reduction and showed that straw return combined with N fertilizer reduction may be a promising practice to maintain mycorrhizal symbiosis concomitantly with crop productivity.

Heavy metal pollution poses a serious hazard to human health, and microbial remediation of heavy metals in soil has been widely studied. A group of ascomycetes classified as dark septate endophytes (DSEs) colonize plant roots and benefit host plants under abiotic stress conditions. In this study, Phragmites australis, a common remediation plant in the Baiyang Lake in North China, was investigated. Soils and roots of P. australis were collected in typical heavy metal-contaminated sites, and the species diversity and community structure of DSEs in P. australis roots were studied. In addition, DSE strains were isolated, cultured, and tested for their tolerance to Cd stress. The results showed that DSEs occurred extensively in P. australis roots, forming typical dark septate hyphae, with a total colonization rate of 19.7%--83.1%. Morphological and internal transcribed spacer sequencing analyses were used to identify 10 species within 9 genera of DSE fungi. Among these fungi, 6 strains with considerable resistance to Cd stress were identified. The biomasses of Poaceascoma helicoides, Alternaria doliconidium, and Acrocalymma vagum strains increased as the Cd levels increased. These results can not only help to understand plant-DSE interactions in wetland environments, but also provide a theoretical basis for making full use of DSE fungi to alleviate heavy metal contamination in soil.

Ammonia (NH₃) emissions, the most important nitrogen (N) loss form, always induce a series of environmental problems such as increased frequency of regional haze pollution, accelerated N deposition, and N eutrophication. Arbuscular mycorrhizal (AM) fungi play key roles in N cycling. However, it is still unclear whether AM fungi can alleviate N losses by reducing NH₃ emissions. The potential mechanisms by which AM fungi reduce NH₃ emissions in five land-use types (grazed grassland, mowed grassland, fenced grassland, artificial alfalfa grassland, and cropland) were explored in this study. Results showed that AM fungal inoculation significantly reduced NH₃ emissions, and the mycorrhizal responses of NH₃ emissions were determined by land-use type. Structural equation modeling (SEM) showed that AM fungi and land-use type directly affected NH₃ emissions. In addition, the reduction in NH₃ emissions was largely driven by the decline in soil${\text{NH}}_4^{+}$-N and pH and the increases in abundances of ammonia-oxidizing archaea (AOA) amoA and bacteria (AOB) amoB genes, urease activity, and plant N uptake induced by AM fungal inoculation and land-use type. The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.

Soil health is an important component of “One Health”. Soils provide habitat to diverse and abundant organisms. Understanding microbial diversity and functions is essential for building healthy soils towards sustainable agriculture. Arbuscular mycorrhizal fungi (AMF) form potentially symbiotic associations with approximately 80% of land plant species that are well recognized for carbon flux and nutrient cycling. In addition to disentangling the signaling pathways and regulatory mechanisms between the two partners, recent advances in hyphosphere research highlight some emerging roles of AMF and associated microbes in the delivery of soil functions. This paper reviews the contribution of AMF to soil health in agroecosystems, with a major focus on recent progress in the contribution of hyphosphere microbiome to nutrient cycling, carbon sequestration, and soil aggregation. The hyphosphere microbiome and fungal stimulants open avenues for developing new fertilizer formulas to promote AMF benefits. In practice, developing AMF-friendly management strategies will have long-term positive effects on sustainable agriculture aiming at simultaneously providing food security, increasing resource use efficiency, and maintaining environment integrity.

Intensive management is known to markedly alter soil carbon (C) storage and turnover in Moso bamboo forests compared with extensive management. However, the effects of intensive management on soil respiration (R_S) components remain unclear. This study aimed to evaluate the changes in different R_S components (root, mycorrhizal, and free-living microorganism respiration) in Moso bamboo forests under extensive and intensive management practices. A 1-year in-situ microcosm experiment was conducted to quantify the R_S components in Moso bamboo forests under the two management practices using mesh screens of varying sizes. The results showed that the total R_S and its components exhibited similar seasonal variability between the two management practices. Compared with extensive management, intensive management significantly increased cumulative respiration from mycorrhizal fungi by 36.73%, while decreased cumulative respiration from free-living soil microorganisms by 8.97%. Moreover, the abundance of arbuscular mycorrhizal fungi (AMF) increased by 43.38%, but bacterial and fungal abundances decreased by 21.65% and 33.30%, respectively, under intensive management. Both management practices significantly changed the bacterial community composition, which could be mainly explained by soil pH and available potassium. Mycorrhizal fungi and intensive management affected the interrelationships between bacterial members. Structural equation modeling indicated that intensive management changed the cumulative R_S by elevating AMF abundance and lowering bacterial abundance. We concluded that intensive management reduced the microbial respiration-derived C loss, but increased mycorrhizal respiration-derived C loss.

Forest trees can establish symbiotic associations with dark septate endophytes (DSEs) and ectomycorrhizal fungi (ECMF) simultaneously. However, the combined effects of these two fungi on the growth and cadmium (Cd) tolerance of host plants remain largely unexplored. To address this knowledge gap, a pot experiment was conducted to examine the effects of the interaction between an ECMF strain (Suillus granulatus) and a DSE strain (Pseudopyrenochaeta sp.) on Pinus tabulaeformis under Cd stress, by assessing plant growth and physiological parameters, nutrient uptake, and soil properties. Notably, the colonization rates of both fungal strains were found to increase in response to Cd stress, with the extent of this increase being influenced by the specific fungal species and the Cd level in the soil. Compared to the non-inoculation treatment, single inoculation with fungal strain resulted in enhanced biomass, root development, and nutrient contents in P. tabulaeformis seedlings under Cd stress. Furthermore, a synergistic effect was observed when these seedlings were co-inoculated with S. granulatus and Pseudopyrenochaeta sp., as indicated by significantly greater measurements in various indicators compared to both the single and non-inoculation treatments. Fungal inoculation effectively regulated the antioxidant defense responses and photosynthesis of P. tabulaeformis seedlings subjected to Cd stress, particularly in the co-inoculation treatment. In addition, fungal inoculation facilitated the Cd accumulation in P. tabulaeformis, suggesting a promising potential for the implementation of bioremediation strategies in the areas contaminated with heavy metals. The findings from this study indicate that the utilization of root symbiotic fungi obtained from stress environments could potentially enhance the growth performance and tolerance of P. tabulaeformis towards heavy metals, and co-inoculation of both fungal groups may result in even more pronounced synergistic effects on the overall fitness of the plant.

Excess available K and Fe in Fe ore tailings with organic matter amendment and water-deficiencies may restrain plant colonization and growth, which hinders the formation of eco-engineered soil from these tailings for sustainable and cost-effective mine site rehabilitation. Arbuscular mycorrhizal (AM) fungi are widely demonstrated to assist plant growth under various unfavorable environments. However, it is still unclear whether AM symbiosis in tailings amended with different types of plant biomass and under different water conditions could overcome the surplus K and Fe stress for plants in Fe ore tailings, and if so, by what mechanisms. Here, host plants (Sorghum sp. Hybrid cv. Silk), either colonized or noncolonized by the AM fungi (Glomus spp.), were cultivated in lucerne hay (LH, C:N ratio of 18)- or sugarcane mulch (SM, C:N ratio of 78)-amended Fe ore tailings under well-watered (55% water-holding capacity (WHC) of tailings) or water-deficient (30% WHC of tailings) conditions. Root mycorrhizal colonization, plant growth, and mineral elemental uptake and partitioning were examined. Results indicated that AM fungal colonization improved plant growth in tailings amended with plant biomass under water-deficient conditions. Arbuscular mycorrhizal fungal colonization enhanced plant mineral element uptake, especially P, both in the LH- and SM-amended tailings regardless of water condition. Additionally, AM symbiosis development restrained the translocation of excess elements (i.e., K and Fe) from plant roots to shoots, thereby relieving their phytotoxicity. The AM fungal roles in P uptake and excess elemental partitioning were greater in LH-amended tailings than in SM-amended tailings. Water deficiency weakened AM fungal colonization and functions in terms of mineral element uptake and partitioning. These findings highlighted the vital role AM fungi played in regulating plant growth and nutrition status in Fe ore tailings technosol, providing an important basis for involvement of AM fungi in the eco-engineered pedogenesis of Fe ore tailings.

Although arbuscular mycorrhizal fungi (AMF) could play important roles in zinc (Zn) uptake in host plants, the effects of AMF on Zn uptake and transport in winter wheat during the whole growth stages remain unclear. A pot experiment was conducted to investigate the effects of Funneliformis mosseae (Fm) and Claroideoglomus etunicatum (Ce) on Zn absorption, transport, and accumulation in winter wheat growing in soils spiked with different Zn levels (0, 2.5, and 25 mg kg⁻¹). The results showed that there was a significant correlation between mycorrhizal colonization rate and Zn absorption efficiency in winter wheat roots during the post-anthesis period, but there was no significant correlation during the pre-anthesis period. Arbuscular mycorrhizal fungi significantly increased Zn concentrations (0.56–1.58 times) in wheat grains under 0 mg kg⁻¹ Zn level, but decreased Zn concentrations in wheat grains under 25 mg kg⁻¹ Zn level. Additionally, at the filling and maturity stages, AMF increased Zn absorption rate and the contribution of root Zn uptake to grain Zn by 3–14 and 0.36–0.64 times, respectively, under 0 mg kg⁻¹ Zn level and 0.21–1.02 and 0.27–0.37 times, respectively, under 2.5 mg kg⁻¹ Zn level. However, AMF decreased root Zn absorption rate (0.32–0.61 times) and increased the contribution of Zn remobilization in vegetative tissues to grain Zn (1.69–2.01 times) under 25 mg kg⁻¹ Zn level. This study would complement the mechanisms and effects of AMF on Zn absorption and transport in winter wheat and provide a potential method for the application of AMF to enrich wheat grain Zn.

Symbiotic fungi are involved in plant flooding tolerance, while the underlying mechanism is not yet known. Since polyamines (PAs) and proline are also associated with stress tolerance, it is hypothesized that the enhancement of stress resistance by symbiotic fungi is associated with changes in PAs and/or proline. The aim of this study was to analyze the effect of inoculation with Funneliformis mosseae and Serendipita indica on plant growth, PAs, and proline and the metabolisms in peach (Prunus persica) under flooding. Two-week flooding did not affect root colonization frequence of F. mosseae, while it promoted root colonization frequence of S. indica. Under flooding, plants inoculated with F. mosseae and S. indica maintained relatively higher growth rates than uninoculated plants. Funneliformis mosseae promoted root ornithine (Orn) contentration and arginine (Arg) and Orn decarboxylase activities under flooding, which promoted putrescine (Put), cadaverine (Cad), and spermidine (Spd) contentrations. Conversely, S. indica decreased contentrations of Arg, Orn, and agmatine and Arg decarboxylase activities, thus decreasing PA contentrations under flooding. Polyamines were negatively correlated with the expression of PA uptake transporter genes, PpPUT1 and PpPUT2, in peach. Polyamine transporter genes of F. mosseae (FmTPO) and S. indica (SiTPO) were regulated by flooding, of which FmTPO1 was positively correlated with Put, Cad, and Spd, along with positive correlations of Spd with SiTPO1, SiTPO2, and SiTPO4. Under flooding, F. mosseae decreased proline concentration, while S. indica increased proline concentration and correlated with expression of a Δ¹-pyrroline-5-carboxylate synthetase gene, PpP5CS2. It was thus concluded that F. mosseae modulated polyamine accumulation, while S. indica induced proline accumulation to tolerate flooding.}