[Rhizospheric Mechanisms of Hemerocallis middendorfii Trautv. et Mey. Remediating Petroleum-contaminated Soil and Metabonomic Analyses of the Root Systems].

: The effects of a special ornamental plant Hemerocallis middendorfii Trautv. et Mey. on remediating petroleum-contaminated soil from the Dagang Oilfield in Tianjin, China, was studied by a greenhouse pot-culture experiment and the gradients of TPHs were 0, 10,000 and 40,000 mg · kg⁻¹. The results suggested that H. middendorfii had a high tolerance to TPHs (≤ 40,000 mg · kg⁻¹). And H. middendorfii significantly (P < 0.05) promoted the removal rate of TPHs (53.7% and 33.4%) compared with corresponding controls (31.8% and 12.0%) by natural degradation, respectively. The relative abundance of amino acids, organic acids and sugars and others in soil were analyzed by gas chromatography-mass spectrometry (GC-MS), and PCA and PLS-DA models were to investigate the rhizospheric mechanisms. The results suggested that H. middendorfii changed the distribution characteristics of each component in soil, and the glucopyranoside played a key role in the removal of TPHs. Furthermore, the results about comparative metabolic profile showed that some special metabolites were only found in the contaminated groups, including alanine, tetradecanoic acid, hexadecanoic acid and 9,12-octadecadienoic acid. Additionally, the exposure of TPHs changed the primary metabolic flux of roots, and caused the significant (P < 0.01) change of metabolites. In conclusion, H. middendorfii might be an enduring ornamental plant for effective remediating TPHs (≤ 40,000 mg · kg⁻¹) in soil. But the exposure of TPHs had changed the metabolic profile of H. middendorfii in roots, which might be the metabolic response of H. middendorfii to petroleum-contaminated soil.