Degradation of exogenous caffeine by Populus alba and its effects on endogenous caffeine metabolism

This is the first study reporting the presence of endogenous caffeine, theobromine, and theophylline in all organs of poplar plants. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used in order to evaluate the uptake, translocation, and metabolism of caffeine-(trimethyl-(13)C) in Populus alba L. Villafranca clone grown in hydroponic conditions. We investigated the remediation of caffeine since it is one of the most widely consumed drugs and it is frequently detected in wastewater treatment plant effluents, surface water, and groundwater worldwide. Our results demonstrated that poplar can absorb and degrade exogenous caffeine without negative effects on plant health. Data showed that concentrations of all endogenous compounds varied depending on caffeine-(trimethyl-(13)C) treatments. In particular, in control conditions, endogenous caffeine, theobromine, and theophylline were mainly distributed in roots. On the other hand, once caffeine-(trimethyl-(13)C) was provided, this compound and its dimethy-(13)C metabolites are mainly localized at leaf level. In conclusion, our results support the possible use of Villafranca clone in association with other water treatment systems in order to complete the process of caffeine remediation

ESI and APCI LC-MS/MS in Model Investigations on the Absorption and Transformation of Organic Xenobiotics by Poplar Plants (Populus alba L.)

Populus alba Villafranca clone was chosen for a proof of concept study to determine the potential uptake and accumulation of xenobiotics by trees. Caffeine, erythromycin, and sodium dodecyl sulphate (SDS) were studied as representative elements of, respectively, widely present organic pollutants, antibiotics, and surfactants. Plants were grown hydroponically and irrigated with a recirculating Hoagland's nutrient solution (control) and Hoagland's nutrient solution fortified with the desired pollutant. Different plantsâ\u80\u99 tolerance was observed in relation to xenobiotics applied. Under caffeine and erythromycin treatments, plants showed good health all over the period of experiments, and no differences in poplar growth were observed. On the contrary diffused necrosis at leavesâ\u80\u99 level was observed when SDS was applied to nutrient solution. Xenobiotics uptake was investigated in roots, stem, and leaves, and quantification was performed using liquid chromatography, coupled with tandem mass spectrometry using selected reaction ion monitoring on a triple quadrupole mass spectrometer, with electrospray or atmospheric pressure chemical ionization, depending on the analyte. All the pollutants were detected in all organs analyzed. Poplar plants also showed an active role in the elimination of the pollutants as some of them were metabolized by the tree

Surfactant and heavy metal interaction in poplar: A focus on SDS and Zn uptake

Surfactants are widely used detergent ingredients and, thanks to their chemical properties, they are applied for remediation of sites polluted by heavy metals and organic contaminants, both in soil flushing and in phytoremediation. However, their direct effects on tree physiology especially in consociation with heavy metal pollution, as well as their possible absorption by plants, have not been appropriately investigated. In order to evaluate plant uptake/translocation of the surfactant sodium dodecyl sulfate (SDS) and the heavy metal zinc (Zn) in Populus alba L. Villafranca clone, SDS was applied alone (0.5 mM) or in combination with Zn (1 mM). Physiological effects on plant growth and photosynthetic performance were investigated. An increasing trend of Zn translocation towards basal leaves as a consequence of SDS co-treatment (1 mM Zn + 0.5 mM SDS; P = 0.03) was observed, proving the ability of SDS to improve heavy metals translocation. However, SDS exposure (both in 0.5 mM SDS and 1 mM Zn + 0.5 mM SDS treated plants) resulted in the appearance of foliar necrosis that expanded with an acropetal trend and finally led to leaf abscission. This phenotype may be caused by the emergence of an additional stress during the experimental trial, which could be related to the dissociation of sodium (Na) ions from the dodecyl sulfate molecules in the hydroponic system. In fact, while liquid chromatography-tandem mass spectrometry measurements revealed that dodecyl sulfate is mainly retained at root levels, Na is translocated to the aerial parts of the plant