Microorganisms carrying cbbL, pmoAand coxLgenes play crucial roles in regulating soil-atmosphere exchanges of carbon trace gases (CO₂, CH₄, and CO). However, the geographical distribution patterns of these functional genes in agricultural ecosystems and their environmental drivers remain poorly understood. Here, we surveyed agricultural soils across four climate zones (tropical, subtropical, warm temperate, and mid-temperate) in eastern China to quantify the abundances of CO₂-assimilating bacteria (cbbLgene), methanotrophs (pmoAgene), and CO-oxidizing bacteria (coxLgene). We found significant ecosystem-specific patterns: the cbbLgene was more abundant in upland soils (averaging 9.46×10⁹ copies g^–1) than in paddy soils (6.44×10⁹copies g^–1). In contrast, methanotrophs abundance was 1 to 3 orders of magnitude higher in paddy (averaging 1.17×10⁸copies g^–1) than in upland (5.78×10⁶ copies g^–1) soils. The coxLgene maintained similar abundance levels across both soil types (averaging 6.12×10⁸vs. 5.91×10⁸copies g^–1).Structuralequation models revealed that spatial factors primarily shaped cbbLand pmoAin uplands, whereas total bacterial abundance was the dominant predictor for all three genes in paddy soils. These results highlight distinct ecological controls on microbial functional groups and provide a predictive framework for how land use and climate change may regulate microbial mediation of carbon gas fluxes across a continental-scale transect in eastern China.

soil organic carbon  /  soil type  /  land use type  /  carbon storage  /  agroecosystems