Variation of macro- and trace elements in organs of the blue honeysuckle subspecies of various environmental and geographic provenance when grown in the Near-Ob forest- steppe (West Siberia, Russia)

The variation limits and organ distribution of mac roand trace elements were determined in plants of the three sub species of Lonicera caerulea L. The leaves, as compared with the stems, were fou nd to accumulate more of B, Са, Mg, Mo, P and Sr and less of Al, Mn, Ti and Zn. The plants of different subspecies, grown on so ils f the similar chemical element composition, showed statistically significant differences in contents and organ distribution patterns of Al, Cr, Cu, Fe, Mg, Mo, Na, Ni, Pb, Si, Ti and Zn. The stems of the subspecies of the Far East provenance ( L. сaerulea subsp. kamtschatica and L. сaerulea subsp. venulosa) had abnormally high contents of Al, Cr, Fe, Na, Si and Ti.

Blue honeysuckles are spread in the taiga zone of Eurasia and North America. On most of their growth area their berries are bitter in taste, and till the middle of the 20 th century the species of the subsection were not even considered as food plants. Only in the Far East, the north of China and Hokkaido Island in Japan the berriess of L. сaerulea subsp. kamtschatica, L. сaerulea subsp. venulosa, L. сaerulea subsp. emphyllocalyx and L. Boczkarnokowae were consumed by humans [2,3]. The native populations of L. сaerulea subsp. kamtschatica and L. сaerulea subsp. venulosa were used as initial sources for breeding the first cultivated varieties. Over the last years the breeding focus shifted towards L. caerulea subsp. Altaica as having a combination of economically valuable traits such as high productivity, rapid production, drought resistance, firm berry fixing and high bioflavonoid content.
Numerous studies proved the beneficial effects of blue honeysuckle berries for human health. The fruit medicinal properties are determined by the high content of biologically active substances (BAS). Alongside with high BAS content, the L. caerulea organs accumulate high levels of macro-and trace elements [4]. There is an interrelationship between accumulation of certain BAS and trace elements, which often show combined medicinal effect [5]. Species specificity of plants in respect to elemental composition and content is of great interest both from the theoretical point of view, i.e. to get a better insight into the fundamental biochemistry of plants, as well as from the practical angle by using plants as food and medicine source.
Our earlier studies of chemical element contents in plants of L. сaerulea subsp. altaica and L. caerulea subsp. pallasii growing in natural populations [4,6] showed substantial variation of macro-and trace element contents in plant organs depending on their growth environment. The aim of this study was to compare macro-and trace elements variation in fruits, leaves and stems of the three L. caerulea subspecies of environmentally and geographically different provenances when grown in culture in the forest-steppe zone in the Near-Ob region (West Siberia, Russia).

Material and methods
For measuring chemical elements in the soil-plant system we performed combined collection of soil and phytomass samples. Leaves, berries and stems of L. caerulea were collected at the ripening stage on the experimental plot in the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences (54° N, 83° E, Novosibirsk, Russia). The samples were collected from the three plants of the three subspecies differing in environmental and geographical provenances: L. caerulea subsp. altaica from the Mountain Altai, L. сaerulea subsp. kamtschatica from the Kamchatka Peninsular and L. сaerulea subsp. venulosa from Primorye region. Chemical elements (Al, B, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sr, Ti, Zn) in soil and phytomass were measured by atomic emission spectrometry after dry combustion. The mobile form content of Ca, Cu, Fe, К, Mg, Mn, Na, Ni, Sr, Zn was evaluated by atomic absorption in ammonium acetate extracts with pH 4.8. The results are given per unit of soil mass on the air-dry basis. Statistical analysis was performed with Excel software.

Results and discussion
Elemental composition of soils on the plot where the honeysuckles were grown was rather homogenous both in bulk and mobile form contents of macro-and trace elements (Table 1, 2). Organ distribution and accumulation of macro-and trace elements showed different patterns ( Table 2). The leaves, as compared with the stems, were found to have higher concentration of ash elements (6.8-8.9 vs. 3.6-4.7%, respectively). This increased ash content was most likely due to the increased (2-3 times higher) accumulation of Са, Mg and P, as well as B, Mo and Sr; the stems were found to accumulate Al, Mn, Pb, Ti and Zn more intensively. The berries, as compared with other organs, contained maximal amounts of K and Ni, the other elements being substantially lower in contents. Trace element distribution between the stems and the leaves was either rather homogenous (Ba, Cu) or showed a more complex pattern, being differential for the plant sample provenance.
Statistically significant difference was revealed between the subspecies in the accumulation rate of certain chemical elements. As compared with L. caerulea subsp. altaica, subspecies of Primorye provenance had extremely high concentrations of Al, Cr, Fe, Na, Si and Ti in their stems, i.e. L. сaerulea subsp. kamtschatica 4.7-7.5 times and L. сaerulea subsp. venulosa 2.4-3.5 times higher.
The found differential accumulation of macro-and trace elements in L. сaerulea subspecies of environmentally and geographically different provenances, as well as the organ distribution patterns when grown on soil of similar chemical element composition strongly suggest that macro-and trace elements uptake mechanisms by plants had been formed in specific environments and fixed genetically.