Al-induced CsUGT84J2 enhances flavonol and auxin accumulation to promote root growth in tea plants

Although Al is not necessary or even toxic to most plants,it is beneficial for the growth of tea plants.However,the mechanism through which Al promotes root growth in tea plants remains unclear.In the present study,we found that flavonol glycoside levels in tea roots increased following Al treatment,and the Al-induced UDP glycosyltransferase CsUGT84J2 was involved in this mechanism.Enzyme activity assays revealed that rCsUGT84J2 exhibited catalytic activity on multiple types of substrates,including phenolic acids,flavonols,and auxins in vitro.Furthermore,metabolic analysis with UPLC-QqQ-MS/MS revealed significantly increased flavonol and auxin glycoside accumulation in CsUGT84J2-overexpressing Arabidopsis thaliana.In addition,the expression of genes involved in the flavonol pathway as well as in the auxin metabolism,transport,and signaling pathways was remarkably enhanced.Additionally,lateral root growth and exogenous Al stress tolerance were significantly improved in transgenic A.thaliana.Moreover,gene expression and metabolic accumulation related to phenolic acids,flavonols,and auxin were upregulated in CsUGT84J2-overexpressing tea plants but downregulated in CsUGT84J2-silenced tea plants.In conclusion,Al treatment induced CsUGT84J2 expression,mediated flavonol and auxin glycosylation,and regulated endogenous auxin homeostasis in tea roots,thereby promoting the growth of tea plants.Our findings lay the foundation for studying the precise mechanisms through which Al promotes the growth of tea plants.

Pilot Test of the Permeable Reactive Barrier for Removing Uranium from the Flooded Gunnar Pit

This work reports on applying iron oxide coated sand (IOCS) media in an experimental permeable reactive barrier to remove uranium (U) species from uranium containing water. A field study was conducted at the legacy Gunnar uranium mine & mill site that was abandoned in the 1960s with limited to no decommissioning. The flooded Gunnar mine pit presently contains about 3.2 million m3 of water contaminated by dissolved U (1.2 mg/L), Ra-226 (0.4 Bq/L), and minor concentrations of other contaminants (As, Se, etc.). The water is seeping over the pit rim into Lake Athabasca, posing potential environmental and health concerns. IOCS media can be used to immobilize uranium species through an adsorption process. Herein, the preparation of hydrous ferric oxide sorbents and their supported forms onto silica sands is described. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (pXRD) were used for structural characterization. The adsorption properties of the IOCS sorbent media were modeled by the Langmuir adsorption isotherm, where a maximum uranium uptake capacity was estimated. Bench-scale adsorption kinetic experiments were also performed before moving to a field trial. Based on these lab results and input on field-scale parameters, a pilot permeable reactive barrier was fabricated and a field test conducted near the Gunnar pit in June 2019. This pilot test provided technical data and information needed for designing a full-scale permeable barrier that employs the IOCS media. This approach can be applied for in-situ water treatment at Gunnar and other legacy uranium sites.

Structural Study of Cellulose-Iron Oxide Composite Materials

There are limited structural studies of iron oxide coated cellulose materials despite their use as adsorbents for the removal of waterborne arsenic species. This study reports on the structural characterization of cellulose-iron oxide composites at variable iron oxide content using spectroscopy methods (Raman, solids 13C NMR, powder X-ray diffraction (pXRD)) and thermal gravi-metric analysis (TGA). Iron oxide was supported onto cellulose (ca. 25 wt.%) without significant loss in the Fe coating efficiency, where the accessibility of the biopolymer -OH groups affect the coating efficiency and yield of the iron oxide-cellulose composite. Isotherm adsorption studies for cellulose, iron oxide species and the cellulose composite materials with roxarsone (3-nitro- 4-hydroxyphenylarsonic acid) were studied to characterize the surface chemical properties of these potential adsorbent materials.