Transcriptomic mechanisms of reduced PM2.5-Pb retention in the leaves of the low-Pb-accumulation genotype of Chinese cabbage.

Atmospheric fine particulate matter (PM2.5) mainly contributes to Pb accumulation in the edible leaves of Chinese cabbage in North China. It was found that a low-Pb-accumulation (LPA) genotype of Chinese cabbage contained less Pb in leaves than high-Pb-accumulation (HPA) genotype exposed to PM2.5-Pb. However, there are no data on the transcriptional regulatory mechanisms of foliar PM2.5-Pb uptake by Chinese cabbage. The present study investigated the retention of PM2.5-Pb in foliar apoplast and symplasm and the underlying molecular mechanisms of reduced Pb in LPA leaves. It appeared more Pb in apoplast and less Pb in symplasm of LPA leaves, whereas the pattern was opposite in HPA. There were 2646 and 3095 differentially expressed genes (DEGs) in LPA and HPA leaves under PM2.5-Pb stress with clearly genotype-specific function, respectively. Furthermore, mRNA levels of XTH16 regulating cell wall thickening, PME2 and PME6 involved in cell wall remodification were significantly expressed in LPA, but not in HPA. Meanwhile, foliar PM2.5-Pb stress downregulated expression of ZIP1, YSL1, and CNGC3 responsible for Pb influx to cell, and upregulated expression of ABCG36 regulated Pb efflux from symplasm in LPA leaves. These results improve our understanding to the mechanisms underlying foliar Pb uptake from PM2.5-Pb at transcriptomic level.

Catalytic synthesis of chloroacetates with thermoregulated ionic liquids based on vanadium-substituted polyoxometalate.

A series of polyoxometalate-based ionic liquid (POM-IL) catalysts with functional sulfonic acid groups, [TEAPS]3+n PW12-n V n O40 (n = 1, 2, 3) were synthesized and characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectrophotometry (FT-IR), UV-Vis spectrophotometry (UV), potentiometric titration and thermogravimetry-differential scanning calorimetry (TG-DSC). The catalytic ability and reusability of the POM-IL catalysts were evaluated on esterification of chloroacetic acid and n-amyl alcohol. The optimum reaction conditions, 0.2 g of the catalyst amount, 10 mL of water carrier, 140 °C of reaction temperature, and 1.2/1 of the molar ratio of alcohol/acid, were obtained by an orthogonal test. [TEAPS]5PW10V2O40 was found to be the best active catalyst with an esterification rate of 98.75% and could be reused five times without significant decrease in activity. The ionic liquid acted as a temperature-responsive catalyst, forming a homogeneous mixture with the reactants at reaction temperature, and could be precipitated and separated from products when the reaction ends at ambient temperature. Therefore, an environmentally friendly and highly efficient approach for the synthesis of chloroacetates is provided.