[Variations in Ozone Concentration in Seven Regions Under Different Temperature and Humidity Conditions].

In recent years, the situation of ozone pollution in China has become increasingly severe, with PM2.5 being the main pollutant in the atmospheric environment of several cities. Meteorological conditions, particularly temperature and humidity, have a great influence on ozone formation. Therefore, understanding and quantifying the impact of the variation in temperature and humidity on ozone level can effectively provide the theoretical basis for the government to prevent and control ozone pollution. By analyzing the relationship among the daily maximum temperature (Tmax), relative humidity (RH), and the maximum 8-h running average ozone (O3-8h) measured from January 1, 2015 to July 31, 2022, a linear positive correlation between O3-8h and Tmax was observed in the seven regions with serious ozone pollution, and the temperature penalty factor ranged from 2.1-6.0 µg·(m3·â„ƒ)-1; a nonlinear correlation between O3-8h and RH was also observed, and O3-8h was the highest when RH was 55%. The sensitivity of different regions to Tmax and RH was slightly different; generally, the most suitable meteorological conditions for ozone formation were 29℃ ≤ Tmax< 38℃ and 40% ≤ RH<70%. In the Yangtze River Delta, Jiangsu-Anhui-Shandong-Henan, and the middle reaches of the Yangtze River, under extreme high temperature conditions (Tmax ≥ 35℃), O3-8h stopped increasing with the increase in temperature and even dropped; simultaneously, it was often accompanied with a small increase in particulate matter. It may be related to the heterogeneous reaction of some precursors with higher water vapor content and the increase in ozone heterogeneous sink.

Pillar-Layered Metal-Organic Frameworks for Sensing Specific Amino Acid and Photocatalyzing Rhodamine B Degradation.

Metal-organic frameworks (MOFs) have presented potential for detection of specific species and catalytic application due to their diverse framework structures and functionalities. In this work, two novel pillar-layered MOFs [Cd6(DPA)2(NTB)4(H2O)4]n·n(DPA·5DMA·H2O) (1) and [Cu2(DPA)(OBA)2]n·n(2.5DMF·H2O) (2) [DPA = 2,5-di(pyridin-4-yl)aniline, H3NTB = 4,4',4''-nitrilotribenzoic acid, H2OBA = 4,4'-oxydibenzoic acid, DMA = N,N-dimethylacetamide, DMF = N,N-dimethylformamide] were successfully synthesized and structurally characterized. Both 1 and 2 have three-dimensional framework structures. The fluorescent property of 1 makes it possible for sensing specific amino acid such as L-glutamic acid (Glu) and L-aspartic acid (Asp). While MOF 2 was found to be suitable for photocatalytic degradation of Rhodamine B (RhB) in the presence of H2O2. The results imply that MOFs are versatile and metal centers are important in determining their properties.

Fluorescent Zn(II) frameworks with multicarboxylate and pyridyl N-donor ligands for sensing specific anions and organic molecules.

Three novel fluorescent Zn(II) frameworks, namely [Zn(DPA)(NDA)]2·2DMF (1), [Zn2(DPA)(OBA)2]·2DMF·4H2O (2) and [Zn(DPA)(HNTB)]·H2O (3) (DPA = 2,5-di(pyridin-4-yl)aniline, H2NDA = 1,4-naphthalenedicarboxylic acid, H2OBA = 4,4'-oxydibenzoic acid, H3NTB = 4,4',4''-nitrilotribenzoic acid, DMF = N,N-dimethylformamide), were successfully fabricated and structurally characterized. Due to the variety of organic linkers, 1-3 exhibit varied topologies: 1 is a 4-c three-dimensional (3D) framework with {65·8} topology, 2 is a 6-c 3D net with point symbol of {44·610·8}, and 3 is a 4-c two-dimensional network that further stacks into a 3D structure by hydrogen bonding interactions with {44·62} topology. Experiments related to fluorescence show that 1-3 can be utilized to quickly identify specific anions of CrO42-/Cr2O72-, and organic molecules such as 2,4,6-trinitrophenol and benzaldehyde.

A single-crystal to single-crystal transition from a 7-fold interpenetrated coordination polymer to a non-interpenetrated one by photochemical [2 + 2] polymerization and their sensing properties.

Two complexes, namely [Zn(bpeb)(sda)] (1) and [Zn(poly-bpeb)(sda)] (2), were synthesized by an organic ligand with an extensively conjugated system, bpeb = 1,4-bis[2-(3-pyridyl) vinyl]-benzene, H2sda = sulfonyldibenzoic acid and d10 metal centers Zn2+. Structural analysis revealed that compound 1 was nonporous and possessed 7-fold interpenetrated three-dimensional (3D) frameworks constructed from one-dimensional (1D) Zn-bpeb and Zn-sda chains. Interestingly, due to the short distance between the vinyl groups from two neighboring bpeb ligands, compound 1 could undergo a photochemical [2 + 2] polymerization reaction to generate 2 in a single-crystal to single-crystal (SCSC) manner under the irritation of UV. Moreover, the organic polymer in 2 could be depolymerized by heating to realize the reversible transformation from 2 to 1. Furthermore, both compounds 1 and 2 could be used as fluorescent sensors for 2,4,6-trinitrophenol (TNP) with high selectivity and sensitivity.

A novel UDP-glycosyltransferase 91C1 confers specific herbicide resistance through detoxification reaction in Arabidopsis.

Plants can reduce or eliminate the damage caused by herbicides and gain herbicide resistance, which is an important theoretical basis for the development of herbicide-resistant crops at this stage. Thus, discovering novel herbicide-resistant genes to produce diverse herbicide-resistant crop species is of great value. The glycosyltransferases that commonly exist in plant kingdom modify the receptor molecules to change their physical characteristics and biological activities, and thus possess an important potential to be used in the herbicide-resistance breeding. Here, we identified a novel herbicide-induced UDP-glycosyltransferase 91C1 (UGT91C1) from Arabidopsis thaliana and demonstrated its glucosylating activity toward sulcotrione, a kind of triketone herbicides widely used in the world. Overexpression of UGT91C1 gene enhanced the Arabidopsis tolerance to sulcotrione. While, ugt91c1 mutant displayed serious damage and reduced chlorophyll contents in the presence of sulcotrione, suggesting an important role of UGT91C1 in herbicide detoxification through glycosylation. Moreover, it was also noted that UGT91C1 can affect tyrosine metabolism by reducing the sulcotrione toxicity. Together, our identification of glycosyltransferase UGT91C1, as a potential gene conferring herbicide detoxification through glucosylation, may open up a new possibility for herbicide resistant breeding of crop plants and environmental phytoremediation.

Rice Glycosyltransferase Gene UGT85E1 Is Involved in Drought Stress Tolerance Through Enhancing Abscisic Acid Response.

Drought is one of the most important environmental constraints affecting plant growth and development and ultimately leads to yield loss. Uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs) are believed to play key roles in coping with environmental stresses. In rice, it is estimated that there are more than 200 UGT genes. However, most of them have not been identified as their physiological significance. In this study, we reported the characterization of a putative glycosyltransferase gene UGT85E1 in rice. UGT85E1 gene is significantly upregulated by drought stress and abscisic acid (ABA) treatment. The overexpression of UGT85E1 led to an enhanced tolerance in transgenic rice plants to drought stress, while the ugt85e1 mutants of rice showed a more sensitive phenotype to drought stress. Further studies indicated that UGT85E1 overexpression induced ABA accumulation, stomatal closure, enhanced reactive oxygen species (ROS) scavenging capacity, increased proline and sugar contents, and upregulated expression of stress-related genes under drought stress conditions. Moreover, when UGT85E1 was ectopically overexpressed in Arabidopsis, the transgenic plants showed increased tolerance to drought as well as in rice. Our findings suggest that UGT85E1 plays an important role in mediating plant response to drought and oxidative stresses. This work may provide a promising candidate gene for cultivating drought-tolerant crops both in dicots and monocots.

IPyA glucosylation mediates light and temperature signaling to regulate auxin-dependent hypocotyl elongation in Arabidopsis.

Auxin is a class of plant hormone that plays a crucial role in the life cycle of plants, particularly in the growth response of plants to ever-changing environments. Since the auxin responses are concentration-dependent and higher auxin concentrations might often be inhibitory, the optimal endogenous auxin level must be closely controlled. However, the underlying mechanism governing auxin homeostasis remains largely unknown. In this study, a UDP-glycosyltransferase (UGT76F1) was identified from Arabidopsis thaliana, which participates in the regulation of auxin homeostasis by glucosylation of indole-3-pyruvic acid (IPyA), a major precursor of the auxin indole-3-acetic acid (IAA) biosynthesis, in the formation of IPyA glucose conjugates (IPyA-Glc). In addition, UGT76F1 was found to mediate hypocotyl growth by modulating active auxin levels in a light- and temperature-dependent manner. Moreover, the transcription of UGT76F1 was demonstrated to be directly and negatively regulated by PIF4, which is a key integrator of both light and temperature signaling pathways. This study sheds a light on the trade-off between IAA biosynthesis and IPyA-Glc formation in controlling auxin levels and reveals a regulatory mechanism for plant growth adaptation to environmental changes through glucosylation of IPyA.

The Arabidopsis UDP-glycosyltransferase75B1, conjugates abscisic acid and affects plant response to abiotic stresses.

KEY MESSAGE: This study revealed that the Arabidopsis UGT75B1 plays an important role in modulating ABA activity by glycosylation when confronting stress environments. The cellular ABA content and activity can be tightly controlled in several ways, one of which is glycosylation by family 1 UDP-glycosyltransferases (UGTs). Previous analysis has shown UGT75B1 activity towards ABA in vitro. However, the biological role of UGT75B1 remains to be elucidated. Here, we characterized the function of UGT75B1 in abiotic stress responses via ABA glycosylation. GUS assay and qRT-PCR indicated that UGT75B1 is significantly upregulated by adverse conditions, such as osmotic stress, salinity and ABA. Overexpression of UGT75B1 in Arabidopsis leads to higher seed germination rates and seedling greening rates upon exposure to salt and osmotic stresses. In contrast, the big UGT75B1 overexpression plants are more sensitive under salt and osmotic stresses. Additionally, the UGT75B1 overexpression plants showed larger stomatal aperture and more water loss under drought condition, which can be explained by lower ABA levels examined in UGT75B1 OE plants in response to water deficit conditions. Consistently, UGT75B1 ectopic expression leads to downregulation of many ABA-responsive genes under stress conditions, including ABI3, ABI5 newly germinated seedlings and RD29A, KIN1, AIL1 in big plants. In summary, our results revealed that the Arabidopsis UGT75B1 plays an important role in coping with abiotic stresses via glycosylation of ABA.

OsIAGT1 Is a Glucosyltransferase Gene Involved in the Glucose Conjugation of Auxins in Rice.

BACKGROUND: In cereal crop rice, auxin is known as an important class of plant hormone that regulates a plethora of plant growth and development. Glycosylation of auxin is known to be one of the important mechanisms mediating auxin homeostasis. However, the relevant auxin glucosyltransferase (GT) in rice still remains largely unknown. RESULTS: In this study, using known auxin glucosyltransferases from other species as queries, twelve putative auxin UDP-glycosyltransferase (UGT) genes were cloned from rice and the one showing highest sequence similarity, named as OsIAGT1, was expressed as recombinant protein. In vitro enzymatic analysis showed that recombinant OsIAGT1 was capable of catalyzing glucosylation of IAA, IBA and other auxin analogs, and that OsIAGT1 is quite tolerant to a broad range of reaction conditions with peak activity at 30 °Ð¡ and pH 8.0. OsIAGT1 showed favorite activity towards native auxins over artificially synthesized ones. Further study indicated that expression of OsIAGT1 can be upregulated by auxin in rice, and with OsIAGT1 overexpressing lines we confirmed that OsIAGT1 is indeed able to glucosylate IAA in vivo. Consistently, ectopic expression of OsIAGT1 leads to declined endogenous IAA content, as well as upregulated auxin synthesis genes and reduced expression of auxin-responsive genes, which likely leads to the reduced plant stature and root length in OsIAGT1 overexpression lines. CONCLUSION: Our result indicated that OsIAGT1 plays an important role in mediating auxin homeostasis by catalyzing auxin glucosylation, and by which OsIAGT1 regulates growth and development in rice.