In recent years, Cadmium (Cd) pollution in soybean farmland is severe. Therefore, this study focused on whether biochar influences soil physiochemical properties, the Cd content in soil and soybean grains, and the abundance and community structure of the czcA gene. Four doses of rice husk biochar (0, 5, 15, and 25 t·ha⁻¹) were applied under continuous cropping and crop rotation systems, and soil samples were collected after four years of one-time addition. The results indicated that biochar addition significantly increased soil available nitrogen, phosphorus, and soil organic carbon contents under continuous cropping and rotation. Biochar application significantly reduced the total Cd content of soil samples and soybean grains. Additionally, biochar application reduced czcA gene abundance in soybean soils by 14.26–37.88% and 35.96–48.71%, respectively. Correlation analysis revealed that Cd content and the abundance of the czcA gene significantly correlated with soil nutrients and pH. High-throughput sequencing revealed that the relative abundances of several Cd-resistant microorganisms were decreased by biochar addition. In addition, adding biochar significantly affected the Cd-resistant microbial community structure and diversity by influencing soil properties and Cd content. Therefore, this study has important practical significance for improving the soil environment and ensuring the quality and safety of agricultural products.

Ammonia−oxidizing archaea (AOA), ammonia−oxidizing bacteria (AOB), and Comammox are key drivers of soil nitrification and play crucial roles in soil nitrogen cycling, with distinct functional contributions. AOA and AOB primarily drive the first step of nitrification by oxidizing ammonia to nitrite, while comammox bacteria can directly oxidize ammonia to nitrate. In this study, quantitative real−time polymerase chain reaction (qPCR) and Illumina MiSeq high−throughput sequencing were employed to determine the absolute abundance, diversity, and community structure of AOA, AOB, and Comammox in alkaline soybean farmland soil under single biochar application. Combined with soil chemical properties, the driving factors shaping ammonia−oxidizing microbial community structure were analyzed to clarify the impact of biochar on ammonia−oxidizing microorganisms from the perspective of soil microbial ecology. The results showed that biochar application effectively modified soil physicochemical properties, increased the absolute abundance of AOA, AOB, and Comammox, influenced their α–diversity, and reshaped community structure. Redundancy analysis revealed that after biochar application, AOA, AOB, and Comammox exhibited positive correlations with soil total phosphorus (TP), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), total organic carbon (TOC), and available potassium (AK). In conclusion, biochar application regulates soil nutrient cycling, particularly by modulating the ammonia oxidation and nitrite oxidation processes, thereby regulating soil nitrogen cycling and ammonia−oxidizing microbial communities, with potential benefits for sustaining soil quality in agricultural systems.

Healthy host plants harbor taxonomically structured and diverse endophytic microbial communities that establish sophisticated symbiotic crosstalk with their hosts. These endophytic microbiomes confer multiple beneficial traits, including growth promotion, nutrient acquisition, and enhanced resistance to biotic and abiotic stresses, and are increasingly recognized as key modulators of plant fitness. The assembly of endophytic communities is not random but shaped by combined effects of environmental cues, host filtering, and microbial–microbial interactions, among which plant immunity constitutes an important host-selection dimension. Beneficial endophytes deploy diverse molecular tactics, such as masking microbe-associated molecular patterns (MAMPs) and secreting immune-suppressive compounds, to evade host PAMP-triggered immunity and effector-triggered immunity (PTI-ETI) surveillance for persistent internal colonization. In this review, based on the literature retrieved from Web of Science Core Collection and Scopus (2010–2026), we systematically summarize the colonization process, dynamic assembly rules, and driving factors of plant endophytic microbiomes. We further elaborate their multifaceted physiological functions in regulating plant growth, nutrient utilization, and stress adaptation. Deciphering such multilayered plant–endophyte interactions provides important insights for harnessing beneficial endophytes to advance sustainable agricultural development.

Soil microorganisms and plant residue decomposition are critical drivers of soil nutrient cycling and multifunctionality, yet their regulatory mechanisms in saline–alkali soils are not fully understood. This study selected bare land and forestland (shrub and tree stands) in Daqing, Heilongjiang, to investigate the effects of plant residue input on forest soil properties, microbial communities, keystone taxa, and multifunctionality using high-throughput sequencing and multivariate analysis. Results showed that plant residue cover significantly improved soil nutrients (SOC, TN, TP, TK, AN), enhanced alkaline phosphatase activity, and increased soil multifunctionality compared with bare land. Plant residues also increased bacterial α-diversity and shifted community composition, with elevated relative abundances of Proteobacteria, Bacteroidota, Planctomycetota, Patescibacteria, and key genera (Mycobacterium, Pseudonocardia, Bryobacter, Steroidobacter). Non-metric multidimensional scaling (NMDS) and correlation analysis revealed microbial communities and keystone taxa were closely correlated with soil nutrients and multifunctionality. Overall, plant residues enhance forest soil multifunctionality by improving soil organic matter, optimizing microbial community structure, and stimulating keystone taxa, providing a scientific basis for understanding microbial-driven nutrient cycling and vegetation restoration in degraded saline–alkali soils.

Soil microorganisms and plant residue decomposition are critical drivers of soil nutrient cycling and multifunctionality, yet their regulatory mechanisms in saline-alkali soils are not fully understood. This study selected bare land and forestland (shrub and tree stands) in Daqing, Heilongjiang, to investigate the effects of plant residue input on forest soil properties, microbial communities, keystone taxa, and multifunctionality using high-throughput sequencing and multivariate analysis. Results showed that plant residue cover significantly improved soil nutrients (SOC, TN, TP, TK, AN), enhanced alkaline phosphatase activity, and increased soil multifunctionality compared with bare land. Plant residues also increased bacterial α-diversity and shifted community composition, with elevated relative abundances of Proteobacteria, Bacteroidota, Planctomycetota, Patescibacteria, and key genera (Mycobacterium, Pseudonocardia, Bryobacter, Steroidobacter). NMDS and correlation analysis revealed microbial communities and keystone taxa were closely correlated with soil nutrients and multifunctionality. Overall, plant residues enhance forest soil multifunctionality by improving soil organic matter, optimizing microbial community structure, and stimulating keystone taxa, providing a scientific basis for understanding microbial-driven nutrient cycling and vegetation restoration in degraded saline-alkali soils.