Prof.  Irina  Shtangeeva
Institute of Earth Sciences, St. Petersburg State University,  Russia

Title: Short-term variations of organic compounds, macro- and trace elements in native plants and in the rhizosphere soil

Abstract:

Our knowledge of the processes regulating the relationships between plants and soil located near plant roots is still insufficient. Elemental composition of different plants can vary depending on various environmental conditions. Among others, temporal fluctuations are of special interest. Until now, more attention has been paid to long-term (seasonal and annual) changes. The information on short-term variations of various organic compounds and many elements in plants and in the rhizosphere soil is limited. Plants have developed special mechanisms to predict the changes in the environment caused by the Earth's rotation. The mechanisms of short-term variations in the concentrations of mineral elements and organic compounds in different plants and in the rhizosphere soil of the plants are still not clearly understood. Meanwhile, it is reasonable to expect that the concentrations of elements in plants can also change over a relatively short time. The variations in the plant element composition under stable conditions have a cyclic nature due to regular rhythms of different biochemical processes. Because photosynthesis is a dominant metabolic process in the primary metabolism of green cells, other plant activities, in particular, nutrient mobilization, are often synchronized with the rhythms of photosynthesis. There is a growing demand for development of rapid high-quality multi-component analytical techniques for efficient identification of different compounds in the rhizosphere soil and in plants. Raman spectroscopy (RS) is a promising non-destructive technique that allows fingerprinting at the molecular level. In our research, RS was applied to determine organic and mineral compounds in soil and plant samples collected from different sites. For the field experiments, several widespread plant species were chosen. The spectra of the plants and soils showed bands of various mineral and organic compounds. It was found that concentrations of carotenoids, phenylpropanoids, aliphatic compounds, cellulose, and carbohydrates in the plant leaves varied both during the day and during the growing season. Although the plants grew under the same conditions and were collected at the same time, the variations were often different on different sampling dates, and there were also differences between sites of sampling. Often, no correlation was found between temperature and humidity fluctuations in sites and daily changes in the content of organic and mineral compounds in plant leaves and in the rhizosphere soil of plants collected at different times. On the other hand, in some cases positive relationships were observed between variations in pH of the rhizosphere soil and daily variations in various compounds in plants and in the soil collected from plant roots. It can be suggested that the main difference in the distribution of the biomolecules in the plants might be because the plant species belong to different groups, monocots and dicots, that differ in many biochemical and physiological functions. Given the short-term variability of organic and mineral compounds in the plants and in the rhizosphere soil, sampling time should be chosen carefully to ensure correct interpretation of experimental data.

Biography:

Affiliation and work address:
Institute of Earth Sciences, St. Petersburg State University, Universitetskaya nab., 7/9, St. Petersburg 199034 Russia, Tel: 007 812 687-61-22, E-mail: shtangeeva@gmail.com

Career/Employment:
2014 – senior researcher,InstituteofEarth Sciences,St. PetersburgUniversity
2006 – 2014 senior researcher, Chemical Department,St. PetersburgUniversity
1999 - 2006 - senior researcher,InterdisciplinaryCenter,St. PetersburgUniversity
1991 -1999 - senior researcher,InstituteofEarth Crust,St. PetersburgUniversity
1983 -1991 - researcher,InstituteofEarth Crust,St. PetersburgUniversity
1979 -1983 - junior research scientist,InstituteofEarth Crust,St. PetersburgUniversity
1978 -1979 - engineer,InstituteofEarth Crust,St. PetersburgUniversity

Main scientific interests:
Ecology, biogeochemistry, multivariate statistics and modelling, modern analytical techniques