Biochemical markers of the functional state of the Stevia rebaudiana and Crambe сordifolia plant-soil ecosystem
Biochemical markers of the functional state of the Stevia rebaudiana and Crambe сordifolia plant-soil ecosystem

Summary/Abstract: A traditional approach to the study of plant-soil ecosystems is based on assessing the main physiological functions of plants (photosynthesis, respiration, mineral nutrition, regulation, protection) and main agronomic characteristics of soil. Such an approach is not very informative, and at the same time it is also time-consuming and expensive, which limits the number of objects that can be studied. Therefore, it is important to identify biochemical markers that can reflect the functional state of phytocoenosis in the most informative way. We analyzed the parameters of basic physiological processes, as well as agronomic and biochemical characteristics of soil in terms of their informative valuesfor understanding the functional state of plant-soil ecosystem using the example of the medicinal plants candyleaf (Stevia rebaudiana (Bart.) Bertoni) and heartleaf crambe (Crambe сordifolia Stev.) from the collection of the M. M. Hryshko National Botanical Garden. In particular, we measured the contents of photosynthetic pigments, sugars, nitrogen (protein), amino acids, and brassinosteroids (BRs) in the plants. Also, we studied the contents of biogenic elements in the plant tissues and soil. The soil was subjected to allelopathic analysis. The study also considered the course of oxidationreduction processes and the contents of phenolic compounds in the soil. The results of the analyses were processed using statistical methods of correlation, factor, discriminant, and cluster analyses. The correlation and factor analysis of the research results showed that the highest factor loadings (≥0.8) were observed for the characteristics of concentration of protective biomolecules (chlorophyll b, BRs). For the soil, the highest factor loadings were recorded for the characteristics of the content of free low-molecular-weight phenolic compounds, allelopathic activity, and redox potential, which are related to the root excretory function. The comparison of the metabolic profiles of Crambe cordifolia and Stevia rebaudiana revealed the species-specific features related to the synthesis of sugars and free amino acids (arginine, cysteine, lysine, and methionine). The allelopathic activity of C. cordifolia and S. rebaudiana is mainly due to low-molecularweight phenolic compounds. Brassinosteroids do not seem to be involved in the allelopathic interactions of the studied species. On the other hand, BRs could be used as a marker for the intensity of assimilation processes in the studied plants.

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