Activation of Bisulfite with Pyrophosphate-Complexed Mn(III) for Fast Oxidation of Organic Pollutants.

Aqueous complexes of Mn(III) ion with ligands exist in various aquatic systems and many stages of water treatment works, while HSO3- is a common reductant in water treatment. This study discloses that their encounter results in a process that oxidizes organic contaminants rapidly. Pyrophosphate (PP, a nonredox active ligand) was used to prepare the Mn(III) solution. An approximate 71% removal of carbamazepine (CBZ) was achieved by the Mn(III)/HSO3- process at pH 7.0 within 20 s, while negligible CBZ was degraded by Mn(III) or HSO3- alone. The reactive species responsible for pollutant abatement in the Mn(III)/HSO3- process were SO4•- and HO•. The treatment efficiency of the Mn(III)/HSO3- process is highly related to the dosage of HSO3- because HSO3- acted as both the radical scavenger and precursor. The reaction of Mn(III) with HSO3- follows second-order reaction kinetics and the second-order rate constants ranged from 7.5 × 103 to 17 M-1 s-1 under the reaction conditions of this study, suggesting that the Mn(III)/HSO3- process is an effective process for producing SO4•-. The pH and PP:Mn(III) ratio affect the reactivity of Mn(III) towards HSO3-. The water background constituents, such as Cl- and dissolved organic matter, induce considerable loss of the treatment efficiency in different ways.

Arabidopsis subtilase SASP is involved in the regulation of ABA signaling and drought tolerance by interacting with OPEN STOMATA 1.

Arabidopsis Senescence-Associated Subtilisin Protease (SASP) has previously been reported to participate in leaf senescence and in the development of inflorescences and siliques. Here, we describe a new role of SASP in the regulation of abscisic acid (ABA) signaling. SASP encodes a subtilase and its expression was considerably induced by darkness, ABA, and ethylene treatments. sasp knockout mutants displayed obvious developmental phenotypes such as early flowering and smaller leaves. In particular, the sasp mutants exhibited enhanced ABA sensitivity during seed germination and seedling growth, heightened ABA-mediated leaf senescence, and increased production of reactive oxygen species (ROS). Importantly, the sasp mutants also showed remarkably increased tolerance to drought, with expression of six ABA signaling-related genes being either up- or down-regulated following ABA treatment. Interaction assays demonstrated that SASP physically interacts with OPEN STOMATA 1 (OST1) at the cell periphery. Co-expression of SASP and OST1 led to degradation of OST1, whereas this degradation was impaired in sasp-1 protoplasts. ROS attenuation assays demonstrated that in sasp-1 mutant guard cells the attenuation rate markedly decreased. Taken together, the results demonstrate that SASP plays an important role in regulating ABA signaling and drought tolerance through interaction with OST1.