Metabolic responses are important for plant adaptation to osmotic stresses. To understand the dosage and duration dependence of salinity effects on plant metabolisms, we analyzed the metabonome of tobacco plants and its dynamic responses to salt treatments using NMR spectroscopy in combination with multivariate data analysis. Our results showed that the tobacco metabonome was dominated by 40 metabolites including organic acids/bases, amino acids, carbohydrates and choline, pyrimidine, and purine metabolites. A dynamic trajectory was clearly observable for the tobacco metabonomic responses to the dosage of salinity. Short-term low-dose salt stress (50 mM NaCl, 1 day) caused metabolic shifts toward gluconeogenesis with depletion of pyrimidine and purine metabolites. Prolonged salinity with high-dose salt (500 mM NaCl) induced progressive accumulation of osmolytes, such as proline and myo-inositol, and changes in GABA shunt. Such treatments also promoted the shikimate-mediated secondary metabolisms with enhanced biosynthesis of aromatic amino acids. Therefore, salinity caused systems alterations in widespread metabolic networks involving transamination, TCA cycle, gluconeogenesis/glycolysis, glutamate-mediated proline biosynthesis, shikimate-mediated secondary metabolisms, and the metabolisms of choline, pyrimidine, and purine. These findings provided new insights for the tobacco metabolic adaptation to salinity and demonstrated the NMR-based metabonomics as a powerful approach for understanding the osmotic effects on plant biochemistry.

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Biogenic volatile organic compounds (BVOCs) emissions lead to fine particulate matter (PM) and ground-level ozone pollution, and are harmful to human health, especially in urban areas. However, most BVOCs estimations ignored the emissions from urban green spaces, causing inaccuracies in the understanding of regional BVOCs emissions and their environmental and health effects. In this study, we used the latest local vegetation datasets from our field survey and applied an estimation model to analyze the spatial-temporal patterns, air quality impacts, health damage and mitigating strategies of BVOCs emissions in the Greater Beijing Area. Results showed that: (1) the urban core was the hotspot of regional BVOCs emissions for the highest region-based emission intensity (3.0 g C m yr) among the 11 sub-regions; (2) urban green spaces played much more important roles (account for 62% of total health damage) than rural forests in threating human health; (3) BVOCs emissions from green spaces will more than triple by 2050 due to urban area expansion, tree growth and environmental changes; and (4) adopting proactive management (e.g. adjusting tree species composition) can reduce 61% of the BVOCs emissions and 50% of the health damage related to BVOCs emissions by 2050.

Rising demand for ruminant meat and dairy products in developing countries is expected to double anthropogenic greenhouse gas and ammonia emissions from livestock by 2050. Mitigation strategies are urgently needed to meet demand while minimizing environmental impacts. Here, we develop scenarios for mitigating emissions under local vs global supply policies using data from 308 livestock farms across mainland China, where emissions intensities are ~50% higher than those in developed nations. Intensification of domestic production and globalized expansion through increased trade result in reductions in global emissions by nearly 30% over a business-as-usual scenario, but at the expense of trading partners absorbing the associated negative externalities of environmental degradation. Only adoption of a mixed strategy combining global best-practice in sustainable intensification of domestic production, with increased green-source trading as a short-term coping strategy, can meet 2050 demand while minimizing the local and global environmental footprint of China’s ruminant consumption boom.

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