紫鸭跖草对土霉素污染水体的修复潜力及根系响应机制

Remediation potential and root response mechanism of Setcreasea purpurea Boom.to oxytetracycline-contaminated water bodies

利用景观植物修复抗生素污染水体对缓解抗生素风险、增加生态效益具有重要意义.以景观观叶植物紫鸭跖草(Setcreasea purpurea Boom.)为受试材料,采用水培实验,探究土霉素(0、30、60、90 mg/L)胁迫28 d对紫鸭跖草叶片抗氧化酶活性、土霉素积累量、根系积累量和根系分泌物的影响.结果表明:(1)紫鸭跖草可以通过激活其体内的活性氧系统来响应较高浓度的土霉素胁迫,其叶片抗氧化系统和丙二醛(MDA)活性与培养液土霉素浓度以及培养时间表现出极显著的交互影响(P<0.01),脯氨酸(Pro)活性与其根部土霉素积累量表现出极显著的正相关关系(P<0.01);(2)紫鸭跖草可在浓度≤90 mg/L土霉素溶液胁迫下长期存活,并大量富集土霉素,在60 mg/L土霉素处理14 d时根系富集浓度最大,富集浓度为2783.6μg/kg;90 mg/L土霉素处理28 d时叶片富集浓度最大,富集浓度为3468.1μg/kg;(3)土霉素胁迫下紫鸭跖草根系分泌物中酯类、醇类、酚类等化合物的相对含量增大,醚类和胺类化合物的分泌量受到抑制.本研究表明紫鸭跖草适用于土霉素污染水体的植物修复,其根系分泌物胁迫响应规律可为调控根际环境提高修复效率提供理论支持.

Landscape plants that remediate antibiotic-contaminated water are important for alleviating the risks of antibiotics and increasing ecological benefits.In this study,the effects of oxytetracycline concentrations(0,30,60,and 90 mg/L)on the leaf antioxidant enzyme activity,oxytetracycline accumulation(in leaves and roots),and root exudates of Setcreasea purpurea were evaluated after 28 d of hydroponic experiments.The results showed that(1)S.purpurea could respond to high concentrations of oxytetracycline stress by activating the reactive oxygen system.The antioxidant enzyme activity and malondialdehyde(MDA)content of the leaves showed significant interaction effects with oxytetracycline concentration in the culture solution and incubation time(P<0.01),and proline(Pro)content was positively correlated with the accumulation of oxytetracycline in the leaves(P<0.01).(2)Oxytetracycline increased in the roots and leaves of S.purpurea over time.The enrichment concentration of oxytetracycline in S.purpurea roots peaked on day 14 after 60 mg/L oxytetracycline treatment,with a maximum concentration of 2783.6μg/kg.The enrichment concentration of oxytetracycline in S.purpurea leaves peaked on day 28 after the 90 mg/L oxytetracycline treatment and the maximum concentration was 3468.1μg/kg.(3)The relative contents of esters,alcohols,phenols,and other compounds in the root exudates of S.purpurea under oxytetracycline stress increased,and the secretion of ethers and amines was inhibited.This study showed that S.purpurea is suitable for the phytoremediation of oxytetracycline-contaminated water bodies,and its root exudate stress response pattern can provide theoretical support for regulating the rhizosphere environment to improve remediation efficiency.