Veterinary antibiotics such as sulfonamides are widely used to increase feed efficiency and to protect against disease in livestock production. The sulfonamide antimicrobial mechanism involves the blocking of folate biosynthesis by inhibiting bacterial dihydropteroate synthase (DHPS) activity competitively. Interestingly, most treatment antibiotics can be released into the environment via manure and result in significant diffuse pollution in the environment. However, the physiological effects of sulfonamide during plant growth and development remain elusive because the plant response is dependent on folate biosynthesis and the concentration of antibiotics. Here, we present a chemical interaction docking model between Napa cabbage (Brassica campestris) DHPS and sulfamethoxazole and sulfamethazine, which are the most abundant sulfonamides detected in the environment. Furthermore, seedling growth inhibition was observed in lentil bean (Lens culinaris), rice (Oryza sativa), and Napa cabbage plants upon sulfonamide exposure. The results revealed that sulfonamide antibiotics target plant DHPS in a module similar to bacterial DHPS and affect early growth and the development of crop seedlings. Taking these results together, we suggest that sulfonamides act as pollutants in crop fields.

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BACKGROUND:There is lack of comprehensive compositional data of the amino acid profile of spinach with regard to different cultivars. A more detailed knowledge in this aspect will be of benefit in the future selection of spinach genotypes with improved nutritional quality. METHODS AND RESULTS:The effects of cultivar type (Jeoncheonhu, Sagyejul, Namdongcho and Mustang) and harvest time (79

In this study, we evaluated the nitrogen (N) mineralization potential and Nitrogen use efficiency (NUE) of oil-cake, compost, hairy vetch and barley, which are the most widely used organic amendments in South Korea. The N mineralization potential (No) for organic fertilizers treated soil was highest for the hairy vetch treatment with a value of 18.9 mg N 100 g , followed by oil-cake, barley and compost. The amount of pure N mineralization potentials in hairy vetch, oil-cake, barley and compost treatments were 8.42, 7.62, 3.82 and 3.60 mg N 100 g -1 , respectively. The half-life (t1/2) of organic N in soil amended with oil-cake fertilizer mineralized quickly in 17 days. While, t1/2 values of organic N for the compost and barley treatments accounted to 44.4 and 44.1 days, respectively. Oil-cake was good in supplying nutrients to plants. Compost and barley inhibited plant growth in the beginning growth stage and this is attributed to N immobilization effect. The results of this study highlight that compost and barley could be used as potential slow release fertilizers in conventional agriculture.

To assess the effect of cold stress on the levels of minerals (C, N, P, K, Ca, Mg, Mn, Zn, Cu and Fe) and water soluble vitamins (B1, B2, B3, B5, B6, B9 and C) in spinach, an experiment was set up under greenhouse conditions and compared to field results. Levels of macro and micronutrients, except iron in spinach were unaffected by growth conditions and cold stress. The abundance of water soluble vitamins were most pronounced in greenhouse grown plants exposed to 14 and 21 days of cold stress. Significant increases in vitamin C (from 22.73 to 34.47 mg 100 g -1 dry matter) accumulation in stressed plants were observed, thus highlighting its role in plant defense mechanisms. Results indicate that cultivation of leafy vegetables in a greenhouse with low temperature (4 to 7°C) exposure for a shorter period (14 to 21 days) before harvest can improve the nutritional quality.