Phosphorus (P) deficiency is an important factor that limits the agricultural production potential in acidic soils. The bacterial phoC gene encodes non-specific acid phosphatase (ACP), which participates in the mineralization of soil organic P and is therefore important for the improvement of soil P availability. However, the function and community population of phoC-harboring bacteria and their driving factors in acidic soil remain largely unknown. For this study, 51 soil samples and 207 plant samples were collected from four locations in the acidic soil region of southern China. Quantitative PCR and high-throughput sequencing were employed to analyze abundance and community composition of phoC-harboring bacteria. The results showed that soil P availability was the important nutrient element limiting the growth of both plants and soil bacteria. Soil ACP activity was clearly higher than alkaline phosphatase, indicating the important effect of phoC-harboring bacteria in acidic soils. ACP activity and phoC gene abundance showed a significant positive correlation, and both were closely related to soil available P, total carbon, and total nitrogen. The dominant genera of phoC-harboring bacteria involved Cupriavidus, Stenotrophomonas, and Xanthomonas. Compared to land-use pattern, sampling location, and soil parent material, soil property played a more important role in affecting phoC-harboring bacterial community structure, where N-related variables including soil NO${}_3^{-}$ -N, NH${}_4^{+}$ -N, and C/N ratio appeared to be the main factors. These findings suggest that phoC-harboring bacteria should provide an important contribution to soil P availability in acidic soil, and its function and community composition were strongly associated with soil nutrients.

Soil acidification is among the primary abiotic stress factors that constrain plant growth. The adoption of acid-tolerant plant varieties and the inoculation of plant growth-promoting rhizobacteria have the distinct advantages of simultaneously increasing soil fertility and ensuring crop growth in acidic soil. However, how acid-tolerant plant varieties interact with the associated rhizosphere microbiota still needs to be explored. In this study, acid-tolerant peanut varieties were screened and planted in natural and sterile environments. The results revealed significant differences in growth performance among the varieties in acidic soil and between natural and sterile environments, revealing that the rhizosphere microbiota is dependent on acid tolerance. Through high-throughput sequencing analysis, the key taxa Sinomonas and Aspergillus were identified, and subsequent greenhouse verification experiments demonstrated their function in promoting peanut plant growth in acidic soil. In total, our findings suggest that the holobiont of tolerant plants and the rhizosphere microbiota is important for stress resistance. This perspective opens up new avenues for improving crop cultivation in soils with different stresses, in which both plant and associated microbial properties are considered.

Straw compost products are considered an excellent organic amendment for acidic soils, yet their effectiveness and microbial associations remain poorly understood. This study employed a pot experiment to evaluate the effects of straw compost products from six crops (corn, soybean, wheat, rice, peanut, and canola) on corn growth and nutrient uptake, soil physicochemical properties, and microbial community in an acidic red soil and examined how microbial community changes relate to plant performance. The results showed that straw compost products significantly enhanced corn growth and contents of nitrogen, phosphorus, and potassium in the aboveground tissues, except for wheat and canola straw. Compost products also improved availability of soil nutrients to varying degrees and affected the bacterial community structures in bulk and rhizosphere soils. There were significant differences in the improvement effects among straw types, with leguminous crops being better than cereal crops. Corn growth was closely correlated with increased soil organic carbon. The influence of the rhizosphere on bacterial communities was stronger than that of straw compost type. The dominant phyla Actinobacteriota and Patescibacteria were key bacterial groups positively associated with corn nutrient uptake in the rhizosphere. Compared to the bulk network, the rhizosphere microbial co-occurrence network exhibited higher modularity and a greater proportion of positive edges, suggesting a more cooperative interaction pattern. The influence of compost products might be associated with distinct nitrogen and phosphorus transformation pathways. Overall, this study clarifies the differential effects of straw compost products on acidic soil improvement and reveals strong associations between rhizosphere microorganisms and crop nutrient uptake.