Nitrogen (N) is one of the most required mineral elements for plant growth, and potassium (K) plays a vital role in nitrogen metabolism, both elements being widely applied as fertilizers in agricultural production. However, the exact relationship between K and nitrogen use efficiency (NUE) remains unclear. Apple dwarf rootstock seedlings (M9T337) were used to study the impacts of different K levels on plant growth, nitrogen metabolism, and carbon (C) assimilation in water culture experiments for 2 years. The results showed that both deficiency and excess K inhibited the growth and root development of M9T337 seedlings. When the K supply concentration was 0 mM and 12 mM, the biomass of each organ, root-shoot ratio, root activity and NO 3 − ion flow rate decreased significantly, net photosynthetic rate (P n) and photochemical efficiency (F v /F m) being lower. Meanwhile, seedlings treated with 6 mM K + had higher N and C metabolizing enzyme activities and higher nitrate transporter gene expression levels (NRT1.1; NRT2.1). 13 C and 15 N labeling results showed that deficiency and excess K could not only reduce 15 N absorption and 13 C assimilation accumulation of M9T337 seedlings, but also reduced the 15 N distribution ratio in leaves and 13 C distribution ratio in roots. These results suggest that appropriate K supply (6 mM) was optimal as it enhanced photoassimilate transport from leaves to roots and increased NUE by influencing photosynthesis, C and N metabolizing enzyme activities, nitrate assimilation gene activities, and nitrate transport.

с помощью высокоэффективной жидкостной хроматографии, совмещенной с массспектрометрией (ВЭЖХ-МС) проведено подробное изучение качественного и количественного состава гинзенозидов в корнях женьшеня настоящего (P. ginseng C. A. Mey.), интродуцированного в условиях Республики Беларусь (опытный участок ЦБС НАН Беларуси). Установлено, что в изученных корнях присутствуют все основные нейтральные гликозиды женьшеня (гинзенозиды Rb 1 , Rc, Rb 2 /Rb 3 , Rd, Rf, Rg 1 и Re), а также их малонилированные производные (малонил-гинзенозиды Rb 1 , Rc, Rb 2 /Rb 3 , Rd, Rg 1 и Re) и некоторые «минорные» гинзенозиды (20-глюко-гинзено-Re) и некоторые «минорные» гинзенозиды (20-глюко-гинзено-) и некоторые «минорные» гинзенозиды (20-глюко-гинзенозид Rf, нотогинзенозиды R 1 и R 2 , изомеры малонил-гинзенозидов Rb 1 и Rd). Показано также, что разные части кор-Rd). Показано также, что разные части кор-). Показано также, что разные части корней P. ginseng существенно отличаются по суммарному содержанию гинзенозидов: для основного корня этот параметр составил 3,3 % от сухой массы, а для боковых корней-7,8 % от сухой массы. Ключевые слова: интродукция, женьшень, Аралиевые, Panax ginseng, Araliaceae, тритерпеновые гликозиды, гинзенозиды, ВЭЖХ-МС Для цитирования: Анализ гинзенозидов в корнях женьшеня настоящего (Panax ginseng), интродуцированного в Центральном ботаническом саду НАН Беларуси / Д. В. Кочкин [и др.] // Докл. Нац. акад. наук Беларуси.-2018.-Т. 62, № 4.-С. 447-454.

Excessive application of nitrogen (N) fertilizer is common in Chinese apple production. High N reduced the contents of soluble sugar and total flavonoids by 16.05 and 19.01%, respectively, resulting in poor fruit quality. Moreover, high N increased the total N and decreased the total C and C/N ratio of apple fruits. On the basis of the transcriptomic, proteomic, and metabolomic analyses, the global network was revealed. High N inhibited the accumulation of carbohydrates (sucrose, glucose, and trehalose) and flavonoids (rhamnetin-3-O-rutinoside, rutin, and trihydroxyisoflavone-7-O-galactoside) in fruits, and more C skeletons were used to synthesize amino acids and their derivatives (especially low C/N ratio, e.g., arginine) to be transferred to N metabolism. This study revealed new insights into the decline in soluble sugar and flavonoids caused by high N, and hub genes (MD07G1172700, MD05G1222800, MD16G1227200, MD01G1174400, and MD02G1207200) and hub proteins (PFK, gapN, and HK) were obtained.

American ginseng (Panax quinquefolium) plants grown at 2 sites in Victoria were analysed for neutral ginsenosides in 7 plant sections at 7 growth stages over a full growing season. Individual ginsenoside concentrations and composition over the growth period were significantly different between plant sections but were similar to those reported for American ginseng grown in other countries. There was thus no detrimental effect of growing American ginseng in a eucalypt environment. The ginsenosides content of both aerial and root sections was at a maximum when fruit were established on the plant. At this maturity, the ginsenosides concentration was highest in the root hair followed by the leaf, lateral root, main root and stem in that order. The leaf contained about 30% of total plant ginsenosides and should be considered as a potential commercial product. This would require plants to be harvested before the current dormant stage when the leaf was still in a viable condition on the plant. A study of the ginsenosides in roots cultivated over a 13-year period revealed that the concentration of ginsenosides was directly correlated with root weight, more than with root age. This suggests that a faster-growing crop will not only have a higher saleable weight but also a higher concentration of ginsenosides.

Refined extracts of Ginkgo biloba L. leaves can protect brain tissue from diverse types of tissue damage. Preliminary experiments identified 6-hydroxykynurenic acid (6-HKA) as a central contributor to this effect, and thus as a potential active marker for drug quality analysis. In contrast, genistein is a negative quality marker for this drug, as high contents of this compound in G. biloba leaves samples are in most cases caused by adulteration with Sophora flavescens Aiton, which is added to the extract by unlawful producers in order to boost its content in flavones, which serve as a quality marker. Some publications even dispute the natural occurrence of genistein in G. biloba leaves altogether, thus claiming that its presence even in trace amounts would prove adulteration. The present study aims to resolve the influence of harvesting time and location on the contents of genistein and 6-HKA-HPLC: Agilent SB-C18 column (5 µm, 4.6x250 mm); phosphoric acid pH2.5, acetonitrile, methanol, gradient; 1 mL/min; 25°C; UV 350 nm-in G. biloba leaves. The lowest contents of 6-HKA were observed in July and August, whereas the maximum was reached in May and October. In the case of genistein-its natural occurrence in G. biloba leaves could be demonstrated under controlled conditions for the first time-the lowest contents were found in May and June, whereas the highest were detected in September and October. These results show that harvesting of G. biloba leaves for pharmaceutical use should be avoided in July and August because of the reduced 6-HKA content, as well as in September and October, the season of highest genistein production. Due to both favorable 6-HKA production and a relative lack of genistein, May was identified as the ideal harvesting month for G. biloba leaves.

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