Combination of biochar and AMF promotes phosphorus utilization by stimulating rhizosphere microbial co-occurrence networks and lipid metabolites of Phragmites

Biochar and arbuscular mycorrhizal fungi promote rapid-cycling Brassica napus growth under cadmium stress

PURPOSE

To explore the mechanisms of tolerance of Brassica napus to ultra-high concentration cadmium pollution and the synergistic effects of biochar (BC) and Arbuscular mycorrhizal fungi (AMF) on plant growth under cadmium (Cd) stress.

RESULTS

The application of 5 % BC and inoculation with 10 g AMF significantly promoted the growth and development of B. napus. The combined application of BC and AMF (BC1A and BC2A) was better than the single application. At the Cd 200 mg/kg level, BC1A increased the fresh weight and Cd content of the above-ground parts of B. napus by 35.5 % and decreased by 21.20 %. The SOD and POD activities increased by 30.63 % and 73.37 %. The MDA and H2O2 contents decreased by 40.8 % and 69.99 %, soluble sugar content increased by 37.96 %. At the Cd 300 mg/kg level, BC1A increased the fresh weight and Cd content of the above-ground parts of B. napus by 32.8 % and decreased by 15.99 %. The SOD and POD activities increased by 39.06 % and 93.56 %. The MDA and H2O2 contents decreased by 28.39 % and 72.45 %, and the soluble sugar content increased by 21.16 %. Overall, both BC and AMF treatments alone or in combination (BC1A) were able to alleviate Cd stress and promote plant growth, with the combination of biochar and AMF being the most effective. Furthermore, transcriptome analyses indicated that BC may improve cadmium resistance in B. napus by significantly up-regulating the expression of genes related to peroxidase, photosynthesis, and plant MAPK signaling pathways. AMF may alleviate the toxicity of Cd stress on B. napus by up-regulating the expression of genes related to peroxisomes, phytohormone signaling, and carotenoid biosynthesis. The results of the study will provide support for ecological restoration technology in extremely heavy metal-polluted environments and provide some reference for the application and popularization of BC and AMF conjugation technology.

Potential Regulatory Effects of Arbuscular Mycorrhizal Fungi on Lipid Metabolism of Maize in Response to Low-Temperature Stress

The specific mechanisms underlying membrane lipid remodeling and changes in gene expression induced by arbuscular mycorrhizal fungi (AMF) in low-temperature-stressed plants are still unclear. In this study, physiological, transcriptomic, and lipidomic analyses were used to elucidate the physiological mechanisms by which AMF can enhance the adaptation of maize plants to low-temperature stress. The results showed that the relative electrical conductivity and malondialdehyde content of maize leaves were decreased after the inoculation with AMF, indicating that AMF reduced the peroxidation of membrane lipids and maintained the fluidity of the cell membrane. Transcriptomic analysis showed the presence of 702 differentially expressed genes induced by AMF in maize plants exposed to low-temperature stress. Furthermore, lipidomic analysis revealed changes in 10 lipid classes in AMF-inoculated maize plants compared with their noninoculated counterparts under low-temperature stress conditions. Lipid remodeling is an important strategy that arbuscular mycorrhizal plants adopt to cope with low-temperature stress.

Co-application of biochars and Piriformospora indica improved the quality of coastal saline soil and promoted the growth of forage

Soil quality is defined as the ability of soil to maintain the soil environment and the biosphere. Due to the limitation of salt and alkali stress, soil quality can be reduced, which in turn affects agricultural production. Biochar is widely used in saline-alkali land improvement because of its special pore structure and strong ion exchange ability, while Piriformospora indica is widely used in saline-alkali land improvement because it can symbiose with plants and improve plant stress resistance. However, the synergistic effect of combined biochar application and inoculation of P. indica on the quality of saline-alkali soil and plant development is uncertain. Hence, we investigated the combined influences of biochar and P. indica on the soil physicochemical characteristics, as well as the growth and chlorophyll florescence of sorghum-sudangrass hybrids (Sorghum bicolor × Sorghum sudane) in our study. The results indicated that after applying biochar and P. indica together, there was a considerable drop in soil pH, conductivity, Na+, and Cl- concentrations. Meanwhile, the soil organic matter (SOM), available phosphorus (AP), and alkaline hydrolyzable nitrogen (AN) increased by 151.81%, 50.84%, and 103.50%, respectively, when the Bamboo biochar was combined with 120 ml/pot of P. indica. Eventually, sorghum-sudangrass hybrid biomass, transpiration rate, and chlorophyll content increased by 111.69%, 204.98%, and 118.54%, respectively. According to our findings, using P. indica and biochar together can enhance soil quality and plant growth. The results also provide insights to enhance the quality of saline-alkali soils and the role of microorganisms in nutrient cycling.

The effect of AMF combined with biochar on plant growth and soil quality under saline-alkali stress: Insights from microbial community analysis

Arbuscular mycorrhizal fungi (AMF) and biochar application individually can enhance plant tolerance to saline-alkali stress and promote plant growth efficiency. However, little is known about the potential synergistic effects of their combination on improving plant growth and soil quality under saline-alkali stress. This experiment adopted the potted method to explore the effects of four treatments on switchgrass growth and soil quality: biochar (BC), Rhizophagus irregularis (Ri), biochar + Ri (BR) and a control without biochar or Ri (CK). Compared to the CK treatment, the switchgrass biomass increased by 92.4 %, 148.6 %, and 177.3 % in the BC, Ri, and BR treatment groups, respectively. Similarly, the rhizosphere soil quality index increased by 29.33 %, 22.7 %, and 49.1 % in the respective treatment groups. The BR treatment significantly altered the rhizosphere soil microbial composition and diversity. Notably, compared to the other treatments, the archaeal α-diversity in the BR group showed a significant decrease. BR treatment significantly increased the relative abundance of bacteria, fungi and archaea at the genus level (e.g., Bacillus, Trichome and candidatus_methanopenens). Network analysis showed that the complexity and closeness of interactions between different microbial taxa were stronger in the BC, Ri and BR treatments than in the CK treatment, with BR being the more prominent. In summary, biochar combined with Ri has a better effect on promoting the growth of switchgrass under saline-alkali stress, improving the quality of saline-alkali soil, and increasing soil microbial diversity. This study provides a new approach for the efficient development and utilization of saline-alkali land.

Lithology and niche habitat have significant effect on arbuscular mycorrhizal fungal abundance and their interspecific interactions

The chemical properties of bedrock play a crucial role in shaping the communities of soil and root-associated arbuscular mycorrhizal fungi (AMF). We investigate AMF community composition and diversity in bulk soil, rhizosphere soil, and roots in karst and non-karst forests. Chemical properties of bedrock of the calcium oxide (CaO) and ratio of calcium oxide and magnesium oxide (Ca/Mg), soil pH, and exchangeable Ca2+ were higher in karst carbonate rocks compared to non-karst clastic rocks. Conversely, bedrock phosphorus content (P-rock), silicon dioxide (SiO2) content, and tree diversity exhibited an opposing trend. AMF abundance was higher in non-karst clastic rocks than in karst carbonate rocks. Stronger interspecific interactions among AMF taxa occurred in the bulk soil and rhizosphere soil of non-karst clastic rocks compared to karst carbonate rocks. AMF abundance and diversity were higher in rhizosphere soil and roots, attributed to increasing nutrient availability when compared to the bulk soil. A more complex network within AMF taxa was observed in rhizosphere soil and roots compared to bulk soil due to an increase in AMF abundance and diversity in rhizosphere soil and roots. Comparing non-karst clastic rocks, karst carbonate rocks increased soil nitrogen (N) and P levels, which can be attributed to the elevated content of soil Ca2+ and Mg2+ content, facilitated by the high CaO content and Ca/Mg ratio in the bedrock of karst forests. However, the thicker soil layer exhibited higher soil nutrient storage, resulting in greater tree diversity in non-karst forests. These findings suggest that high tree richness may increase root biomass and secretion of root exudates in non-karst regions, thereby enhancing the abundance of AMF and their interspecies interactions. Consequently, the diverse bedrock properties that drive variations in soil properties, nutrients, and plant diversity can impact AMF communities, ultimately promoting plant growth and contributing to vegetation recovery.

Combined contribution of biochar and introduced AM fungi on lead stability and microbial community in polluted agricultural soil

Introduction

Lead (Pb) pollution in agricultural soil has been accelerated by industrial development and human activities, and poses a major threat to agricultural ecosystems. Both biochar and arbuscular mycorrhiza (AM) fungi are considered to play an important role in remediation of Pb contaminated soil.

Methods

The combined remediation effects of introduced AM fungi and biochar on soil properties, Pb availability, microbial community and functional profiles were systematically investigated in unsterilized Pb-polluted agricultural soil.

Results

Results indicated that soil nutrients were significantly improved through the combined application of biochar and introduced AM fungi. The introduced AM fungi combined with biochar prepared at 400°C and 500°C promoted the transformation of Pb to a more stable state with low bioavailability. Moreover, the addition of AM fungi and biochar affected the relative abundances of dominant bacteria and fungi at the phylum and genus levels. Biochar mainly affected soil bacterial community and obviously increased the relative abundance of Actinobacteria and Blastococcus. The interactions between biochar and introduced AM fungi mainly affected fungal community, and increased the abundance of Ascomycota and Botryotrichum. Further, PICRUSt analysis indicated biochar amendment supported stronger bacterial metabolic functional potentials.

Discussion

Therefore, the combined application of biochar and Therefore, the combined application of biochar and introduced AM fungi could improve soil nutrients, reduce Pb introduced AM fungi could improve soil nutrients, reduce Pb availability, availability, and show and show a positive effect on a positive effect on indigenous microbial communities and indigenous microbial communities and metabolic functions in metabolic functions in farmland soil.

Biochar immobilized plant growth-promoting rhizobacteria enhanced the physicochemical properties, agronomic characters and microbial communities during lettuce seedling

Spent mushroom substrate (SMS) is the by-products of mushroom production, which is mainly composed of disintegrated lignocellulosic biomass, mushroom mycelia and some minerals. The huge output and the lack of effective utilization methods make SMS becoming a serious environmental problem. In order to improve the application of SMS and SMS derived biochar (SBC), composted SMS (CSMS), SBC, combined plant growth-promoting rhizobacteria (PGPR, Bacillus subtilis BUABN-01 and Arthrobacter pascens BUAYN-122) and SBC immobilized PGPR (BCP) were applied in the lettuce seedling. Seven substrate treatments were used, including (1) CK, commercial control; (2) T1, CSMS based blank control; (3) T2, T1 with combined PGPR (9:1, v/v); (4) T3, T1 with SBC (19:1, v/v); (5) T4, T1 with SBC (9:1, v/v); (6) T5, T1 with BCP (19:1, v/v); (7) T6, T1 with BCP (9:1, v/v). The physicochemical properties of substrate, agronomic and physicochemical properties of lettuce and rhizospheric bacterial and fungal communities were investigated. The addition of SBC and BCP significantly (p < 0.05) improved the total nitrogen and available potassium content. The 5% (v/v) BCP addiction treatment (T5) represented the highest fresh weight of aboveground and underground, leave number, chlorophyll content and leaf anthocyanin content, and the lowest root malondialdehyde content. Moreover, high throughput sequencing revealed that the biochar immobilization enhanced the adaptability of PGPR. The addition of PGPR, SBC and BCP significantly enriched the unique bacterial biomarkers. The co-occurrence network analysis revealed that 5% BCP greatly increased the network complexity of rhizospheric microorganisms and improved the correlations of the two PGPR with other microorganisms. Furthermore, microbial functional prediction indicated that BCP enhanced the nutrient transport of rhizospheric microorganisms. This study showed the BCP can increase the agronomic properties of lettuce and improve the rhizospheric microbial community.