Free Amino Acid Accumulation in Soil and Tomato Plants (Solanum lycopersicum L.) Associated with Arsenic Stress

Abstract

© 2019, Springer Nature Switzerland AG. Pollution of soils with arsenic leads to changes in biochemical processes both in the soil and in plants growing on it. Biochemically active compounds, such as free amino acids, strongly respond to the increase of the content of toxic substances in the environment. This article deals with the changes in the concentration of free amino acids in soil, roots, and aboveground biomass of tomato plants that took place when soil was contaminated with arsenic. Pre-grown tomato plants (Solanum lycopersicum L.) were transplanted into containers with soil contaminated with arsenate (As(V)) at the doses of 50 and 200 mg kg−1. In the soils, roots, and aboveground parts of plants, the changes in the concentration of 16–17 free amino acids were studied by the method of high-performance liquid chromatography. The results of the experiment showed that soil contamination with arsenic can lead to an increase in the concentration of all studied amino acids, both in soils and in tomato plants. Total free amino acid concentration in soil increased by 194.2% at 50 mg kg−1 of As(V) and by 349.6% at 200 mg kg−1 of As(V), in roots and aboveground biomass their concentration increased from 1.5 to 4.6 times. A particularly strong increase of concentration in soil was observed for serine and glycine, whereas in plant tissues, in comparison with other amino acids, aspartic and glutamic acids were intensively accumulated. The strong correlation between the content of free amino acids in the soils and in the roots (r = 0.85) or aboveground biomass of plants (r = 0.88) shows that both soil and tomato plants respond to soil contamination with As(V) in a similar way. However, the results of the study also showed that increasing of amino acid concentration in plant tissues in case of arsenic contamination can be associated with both their accumulations due to the plant’s response to stressful conditions and probably their uptake from the soil.