title: Response of low-molecular-weight organic acids in mangrove root exudates to exposure of polycyclic aromatic hydrocarbons.
abstract: Low-molecular-weight organic acids (LMWOAs) represent an important component of root exudates. They play a pivotal role in the degradation of polycyclic aromatic hydrocarbons (PAHs) in sediments as they influence PAH bioavailability and degrader colonization. This study examined variations of LMWOAs in mangrove root exudates (Aegiceras corniculatum and Kandelia obovata) after exposure in phenanthrene and pyrene solution for 7 and 40 days, respectively. After 7 days of treatment, total root exudates and six types of LMWOA in root exudates from both mangrove species were enhanced. The largest increase was found in oxalic acid, i.e., the dominant component in determined LMWOAs. Coupled with the enhancement in LMWOA exudation rates, root metabolism intensities, measured as the dehydrogenase activity, increased. In contrast, after 40 days of exposure, the exudation rate of total LMWOAs had dropped markedly in PAH-contaminated groups compared to the control, indicating that PAHs negatively impacted root metabolism and activities due to their toxicity. The largest decrease was also found in oxalic acid, suggesting that the biological reactions related with oxalic acid are vulnerable under PAH stresses.
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361005, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361005, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xie
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361005, China.
authors.forename: Haoliang
authors.initials: H
authors.lastname: Lu
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361005, China.
authors.forename: Jingchun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361005, China. ycl@xmu.edu.cn.
authors.forename: Chongling
authors.initials: C
authors.lastname: Yan
mesh_terms: D009930:Organic Chemicals / Q000378:metabolism; D010616:Phenanthrenes; D018517:Plant Roots / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons; D043982:Rhizophoraceae / Q000378:metabolism
chemical_list: D009930:Organic Chemicals; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; C031181:phenanthrene
keywords: Low-molecular-weight organic acids; Mangrove plants; PAHs; Root exudates; Toxicity; Variation