Metabolite Profile of *Amaranthus tricolor* L. and *Amaranthus cruentus* L. in Adaptation to Drought

*Svetlana Motyleva, Murat Gins, Valentina Gins, Nikolay Tetyannikov, Ivan Kulikov, Ludmila Kabashnikova, Daria Panischeva, Maria Mertvischeva and Irina Domanskaya*

#### **Abstract**

The Federal Research Center of Vegetable Growing has developed the cultivars Valentina (*Amaranthus tricolor* L.) and Krepysh (*Amaranthus cruentus* L.), which are successfully grown in several regions of Russia. The dry periods observed in recent years have a negative impact on the development of plants. The red-colored vegetable cultivar demonstrated a higher level of adaptability to drought than the green-colored grain cultivar. It was found that only in the leaves of cv. Valentina multiple spiked crystals consisting of four elements were formed, the predominant proportion belonged to Ca (38.59), then P (0.48), Mg (0.25), and K (0.16) followed, weight%, respectively. Under the conditions of moisture deficiency, the antioxidant activity of water and ethanol extracts in the leaves of both types of amaranth increased from 1.5 to 2.5 times. It was established that under drought conditions, the carbohydrate metabolism and the synthesis of secondary metabolites change. The leaves of the new cultivar of amaranth Valentina are a promising and reproducible source of antioxidants and can be used to create phytobiological preparations. The increased level of the main macro- and microelements—Ca, K, P, Mg, Mo, S and Cl in the seeds of cv. Valentina and Krepysh makes these cultivars promising for use in the food industry.

**Keywords:** amaranth, leaves, photosynthetic pigments, low-molecular-weight metabolites, ash composition of seeds

#### **1. Introduction**

Among abiotic stresses, drought is widely spread and strengthens from year to year all over the world. The stressful influence of drought conditions causes changes in morphological, physiological, and metabolical processes of plants that decrease the productivity and the quality of agricultural crops after all [1]. Molecular indicator of water stress is, first of all, speeded accumulation of active forms of oxygen that leads to the development of water stress, the change of chlorophylls structure, the decrease of photosynthetic pigments and metabolites, and the damage of plants cells [2–5].

Phenolic compounds and flavonoids are the most important and widely spread secondary products of plants. These metabolites enlarge enzymic antioxidant system and possess essential potential to decrease and prevent the cell damage [6]. Mineral elements are not only used as structural components, but also play an important role in the enzymes activity, osmotic pressure control for the cells' turgor and growth, take part in acid-base and water-salt metabolism [7–9]. Increased stability to drought mostly depends on the mineral composition of the plants [10, 11].

The most important and actual problem of genetic-breeding research studies is to determine the crops that are stable to drought. Metabolomic approach is a new direction of molecular-genetic research studies to identify the changes in plants under the influence of adverse environmental factors and to assess their nutritional value. Though, nowadays, the use of this approach remains a little used and poorly studied direction of breeding.

The fundamental knowledge about the characteristics of the leaves, seeds, and flour is crucial for the promotion of the crop for use in the food industry. The *Amaranthus tricolor* L.(cv. Valentina) leaf extracts do not only have beautiful crimson color, they also contain a large number of biologically active substances and can be used for tea drinks preparation. Amaranth gluten-free flour can be used for dietary bakery. This study is a first step toward a more efficient and successful application of amaranth as a commercially available pseudo-grain crop.

*A. tricolor* L. and *Amaranthus cruentus* L. species have been introduced and successfully grown in the Central region of Russia. However, during summer months, the dry period affects the productivity of these species negatively. Based on the foregoing, the present research work was also planned to evaluate and study the mechanisms of drought resistance of two species of amaranth under the conditions of artificial abiotic stress caused by drought.
