Airborne lead: A vital factor influencing rice lead accumulation in China.

Traditionally, lead (Pb) in rice grains has been thought to be mostly derived from soil, and the contribution of aerosol Pb remains so far unknown. Based on a meta-analysis, we surprisingly found rice Pb content decreased proportionally with urban atmospheric Pb concentrations in major rice-growing provinces in China during 2001-2015, suggestive of the strong influence of long-range Pb transport on agricultural environment. With the combination of field survey, field experiment, as well as a predictive model, we confirmed high contribution of atmospheric exposure to rice grain Pb in China. We for the first time developed a predictive mathematical model which revealed that aerosol Pb accumulation ratios of rice grains were related to both grain weight and accumulation types. We successfully predicted the national-scale rice Pb in China on the basis of the public data of urban PM2.5 from 19 rice-growing provinces and proposed a seasonal atmospheric Pb limit of 0.20 µg m-3 based on the safe threshold level of Pb in rice, which was much lower than the current limit of 1 µg m-3 set in China.

Role of hydrogen cyanamide (HC) in grape bud dormancy release: proteomic approach.

In the present study, we identified changes in protein expression patterns of grapevine buds when treated with hydrogen cyanamide (HC). HC induced a shift of more than 2-folds in the expression of 1250 proteins out of approximately 7000 detected proteins. The majority of the differentially expressed proteins (DEPs) were localized in the chloroplast (419) and cytoplasm (347). Most of the detected DEPs were linked with energy metabolism, redox activity, hormone, and stress signaling. Particularly, the DEPs associated with defense and sugar metabolism showed significantly higher expression in HC-treated buds. Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed significant enrichment for circadian rhythm, ribosome, and metabolic pathways. Moreover, the antioxidant activity of peroxidase (POD) increased at initial stages but declined at later stages (18 days post-treatment). This study identified several dormancy-related proteins that regulated signaling, as well as metabolic pathways upon HC application. The outcome of this study provides insights into the role of HC in dormancy release for grapevine production, hence useful to alleviate yield losses in mild winter regions.

[Comparison of major bioactive components from leaves of Chrysanthemum morifolium].

Leaves of Chrysanthemum morifolium were potential medicinal resource. The present study aims to estimate the main bioactive components: total flavonoids (TF), galuteolin (GA), quercitrin (QU), chlorogenic acid (CA) and 3 ,5-O-caffeoylquinic acid ( CQ), which were considered to be the main effective components, in leaves of C. morfolium cultivars in China. The TF content was estimated hy UV-VIS spectrophotometry, while GA, QU, CA, and CQ were quantitatively determined by HPLC. The highest TF content (7. 13% w/w) was found in cultivar Wan Cong (Shexian county). Cultivar Da Bo ( Bozhou county) had the highest GA content (33. 45 mg - g-1); Cultivar Hong Xin (Sheyang county) contained the highest QU content (29.25 mg · g(-1)); Cultivar Chang Ban (Sheyang county) had the highest CA content (13.14 mg ·(-1)). The maximum CQ content (7.35 mg · g(-1)) was observed in culti- r Da Yang ( Tongxiang county). Different cultivars of C. morfolium had significant difference in components, but the leaf and capitulum of C. morifolium. were found to possess similar chemical compositions. The high content of bioactive components in several cultivars suggested the potential utilization of C. morifolium leaves.

Plant uptake and the leaching of metals during the hot EDDS-enhanced phytoextraction process.

Using pot experiments, the effect of the application of the biodegradable chelating agent S,S-ethylenediaminedisuccinic acid (EDDS) in hot solutions at 90 degrees C on the uptake of Cu, Pb, Zn, and Cd by corn (Zea mays L. cv. Nongda No. 108) and beans (P vulgaris L. white bean), and the potential leaching of metals from soil, were studied. When EDDS was applied as a hot solution at the rate of 1 mmol kg(-1), the concentrations and total phytoextraction of metals in plant shoots exceeded or approximated those in the shoots of plants treated with normal EDDS at the rate of 5 mmol kg(-1). On the other hand, the leaching of Cu, Pb, Zn, and Cd after the application of the hot EDDS solution at the rate of 1 mmol kg(-1) was reduced by 46%, 21%, 57%, and 35% in comparison with that from the application of normal EDDS at 5 mmol kg(-1), respectively. For treatment with 1 mmol kg(-1) of EDDS, the leached metals decreased to the levels of the control group (that without EDDS amendment) 14 d after the application of EDDS. The soil amendment with biodegradable EDDS in hot solutions may provide a good alternative to chelate-enhanced phytoextraction in enhancing metal uptake by plants and limiting metals from leaching out of the soil.

[Effects of Cd stress on photosynthetic characteristics and nutrient uptake of cabbages with different Cd-tolerance].

With solution culture, this paper studied the plant growth, photosynthetic characteristics and nutrient uptake of two cabbage (Brassica oleracea L.) cultivars with different Cd-tolerance under treatments of 0, 20, 50 and 100 micromol Cd x L(-1). The results showed that the growth of Cd-sensitive cultivar Qiufeng was inhibited obviously even under low Cd concentration (20 micromol x L(-1)) stress. The net photosynthetic rate (P9, stomata1 conductance (Gs), photochemical efficiency of PS II (Fv/Fm) and quantum yield of electron flow through PS II (phi (PS II)) in its leaves and the dry weight of its shoots and roots declined sharply. However, negative impact on the growth and photosynthetic characteristics of Cd-tolerant cultivar Beinongzaosheng was only observed under high Cd concentration (50 and 100 micromol x L(-1)) stress. Cd stress decreased the contents of chlorophyll a and b, especially of chlorophyll b, which could be an important factor of photosynthesis inhibition. Under Cd stress, the Mn uptake by plant decreased significantly, and the transportation of Fe and Mg from roots to shoots was restrained, which were more obvious in Cd-sensitive than in Cd-tolerant cultivar. Cd stress promoted the P and S uptake by Cd-tolerant cultivar, but opposite results were observed in Cd-sensitive cultivar. Therefore, physiologically, the decrease of Mn, Fe, Mg, S and P concentrations in Cd-sensitive cultivar's leaves under Cd stress was the key reason for the restraint of leaf photosynthesis, and the decrease of plant growth.

[Research of polysaccharide from Dioscorea opposita Thunb].

OBJECTIVE: To isolate a homogeneous polysaccharide RP from RDP (a crude polysaccharide from Dioscorea opposita Thunb.) , and study its preliminary composition and structure. METHODS: RP was obtained with water extraction, alcohol sedimentation, CTAB deprotein, cellulose column and SephadexG-100 column. The purities of RP were identified by SephadexG-200. PC analysis on its acidic hydrolysates was used to determine the sugar components. Sephadex chromatography was used to mensurate its molecular weight. IR was used to analysis RP. RESULTS: RP was homogeneous. IR indicated that RP had beta configurations. The compositon was identified by paper chromatography as glucose, D-mannose, D-galactose. CONCLUSION: The research could provide a theoretical foundation for further development and utilization.

Lead phytoextraction from contaminated soil with high-biomass plant species.

In this study, cabbage [Brassica rapa L. subsp. chinensis (L.) Hanelt cv. Xinza No 1], mung bean [Vigna radiata (L.) R. Wilczek var. radiata cv. VC-3762], and wheat (Triticum aestivum L. cv. Altas 66) were grown in Pb-contaminated soils. Application of ethylenediaminetetraacetic acid (EDTA) (3.0 mmol of EDTA/kg soil) to the soil significantly increased the concentrations of Pb in the shoots and roots of all the plants. Lead concentrations in the cabbage shoots reached 5010 and 4620 mg/kg dry matter on Days 7 and 14 after EDTA application, respectively. EDTA was the best in solubilizing soil-bound Pb and enhancing Pb accumulation in the cabbage shoots among various chelates (EDTA, diethylenetriaminepentaacetic acid [DTPA], hydroxyethylenediaminetriacetic acid [HEDTA], nitrilotriacetic acid [NTA], and citric acid). Results of the sequential chemical extraction of soil samples showed that the Pb concentrations in the carbonate-specifically adsorbed and Fe-Mn oxide phases were significantly decreased after EDTA treatment. The results indicated that EDTA solubilized Pb mainly from these two phases in the soil. The relative efficiency of EDTA enhancing Pb accumulation in shoots (defined as the ratio of shoot Pb concentration to EDTA concentration applied) was highest when 1.5 or 3.0 mmol EDTA/kg soil was used. Application of EDTA in three separate doses was most effective in enhancing the accumulation of Pb in cabbage shoots and decreased mobility of Pb in soil compared with one- and two-dose application methods. This approach could help to minimize the amount of chelate applied in the field and to reduce the potential risk of soluble Pb movement into ground water.