土壤-蒜苗系统中抗生素抗性基因分布特征与迁移机制OA

To investigate the pollution distribution characteristics,migration patterns,and driving factors of antibiotic resistance genes(ARGs)in a soil-garlic seedling(Allium sativum L.)system.Soil,root,and leaf samples were collected from garlic seedlings at four greenhouse cultivation bases.High-throughput quantitative PCR(HT-qPCR)was employed to quantify the abundance of ARGs and integrons.Soil physicochemical properties were determined using standard chemical analysis.Microbial community structure was characterized via 16S rRNA gene high-throughput sequencing.Spearman correlation analysis,Adonis tests,and Network analysis were employed to elucidate the associations between ARGs and environmental factors.The results showed that a total of 186 distinct ARGs were detected across the soil-garlic seedling system.The relative abundance of ARGs exhibited a gradient attenuation pattern:soil>root>leaf.The dominant ARGs also shifted with plant compartment:mexF dominated in soil,mexF or tetQ dominated in root,and tetQ dominated in leaf.Correlation analysis revealed that soil pH,soil organic matter(SOM),and total nitrogen(TN)were significantly negatively correlated with multiple ARGs(P<0.01),while ammonium nitrogen(NH+4-N)significantly promoted ARG enrichment(P<0.01).The intI-1(clinic)and cIntI-1(class 1)were only detected in soil and root.They showed highly significant positive correlations with mexF,sul1,tetG-01,and tetQ in soil(P<0.01),but only with tetQ in root(P<0.01).Efflux pump-mediated ARGs(mexF,tetG-01,floR and oprJ)showed significant correlations(P<0.05)with various dominant bacterial families and functional genes,indicating broad host adaptability and potential for horizontal transfer.Endophytic bacterial families(norank_o_Chloroplast,Mitochondria)in roots and leaves were significantly negatively correlated with ARGs(P<0.05),whereas most dominant soil bacterial families showed significant positive correlations with ARGs(P<0.05).Our results indicated that soil serves as the primary reservoir for ARGs.The root and leaf tissues of garlic seedlings were observed to form a biological barrier to ARG migration via selective enrichment.Soil physicochemical properties(notably NH+4-N),horizontal gene transfer mediated by integrons,and specific soil microbial communities significantly influence(P<0.05)the distribution and migration of ARGs within the soil-garlic seedling system.