Yiming Wang

The rhizosphere microbiome is critical for plant health, yet how soil type and intensive management jointly govern its assembly remain unclear. Here, we hypothesized that soil type acts as a primary environmental filter, while intensive cultivation (plant growth plus fertilization) imposes additional selective pressures that differentially shape bacterial versus fungal communities. Using flue-cured tobacco (K326) grown in clay loam and sandy loam soils under field conditions, we examined the rhizosphere microbiome at the topping stage. Intensive cultivation significantly altered rhizosphere physicochemical properties. Key nutrients, including organic matter (OM), dissolved total nitrogen (DTN), available phosphorus (AP), and available potassium (AK), were markedly enriched. Rhizosphere soil pH exhibited a bidirectional shift relative to the corresponding bulk soil, converging to a narrow range (7.4–7.8) in both soil types. Root activity and fertilization imposed contrasting selective pressures on the two microbial kingdoms: bacterial diversity declined slightly, indicating strong deterministic selection, whereas fungal diversity increased, reflecting adaptation to root-generated niches. Differential abundance analysis identified 38 bacterial OTUs as a core rhizosphere-adapted microbiome shared across both soil types, demonstrating robust fitness in the nutrient-enriched rhizosphere environment under intensive management. No shared core fungal OTUs were detected, underscoring strong soil legacy effects and higher habitat specificity in fungi. Notably, the core bacterial microbiome was dominated by K-strategists (slow-growing, resource-efficient taxa) that exhibited opportunistic traits capable of rapidly exploiting nutrient pulses in the rhizosphere. Together, these findings reveal that soil type acts as a critical filter modulating plant–microbe interactions under intensive agriculture, while bacteria and fungi employ divergent ecological strategies in response to selection pressures. This work provides both theoretical and practical insights for optimizing tobacco cultivation and sustaining soil microecological health.

Understanding how long-term phosphorus (P) fertilization reshapes soil microbiomes and their functional interplay with P cycling is crucial for sustainable agriculture. This study investigated the effects of different P levels on soil physicochemical properties, phosphatase activities, and the bacterial community across three geographically distinct tobacco-growing sites (YD, SH, and ZS) in Fujian Province, China. Our results revealed a significant positive correlation between soil available phosphorus (AP) and phytase ( R = 0.92), challenging the classical P deficiency induction paradigm. Site-specific environment was the paramount factor overriding contemporary P levels in shaping the bacterial community structure and its P-cycling genetic potential. At the broadest scale, stochastic processes dominated the assembly of regional species pools, leading to distinct community templates across sites. Within each site, however, the local P levels acted as a deterministic filter, fine-tuning community composition primarily through species replacement rather than wholesale restructuring. Functional prediction revealed site-specific P-cycling strategies: the YD community showed a higher predicted genetic potential toward aggressive P acquisition (mineralization and solubilization), whereas SH and ZS communities exhibited a higher predicted potential for P scavenging, storage, and recycling (polyphosphate degradation and transport). Redundancy analysis linked these functional profiles to distinct local soil properties: organic matter (OM) at YD, a combination of OM and multiple nutrients at SH, and potassium at ZS. In conclusion, microbial-mediated P cycling in these soils may be governed by a hierarchical mechanism: site-specific context sets the community template, localized soil properties (OM, K) shape the functional repertoire, and current P management modulates the system through species sorting and likely transcriptional regulation. This underscores the need for site-specific, ecological precision management strategies that target dominant local environmental drivers to foster microbial communities capable of optimizing soil P efficiency.