The influence of aromatic amino acids on the chemical composition of mint plants genus (Mentha L.)

Abstract

The aromatic amino acids, tryptophan, phenylalanine and tyrosine, are not only components of proteins, but also precursors of many compounds in plants that have a significant impact on their growth, development, reproduction and protective function against various abiotic and biotic factors. With the growing demand for plant-derived chemical compounds, much in vitro and in vivo research is being conducted to intensify the synthesis of these compounds or to change their qualitative composition in plants. The aim of the research was to evaluate the influence of aromatic amino acids on the chemical composition of different varieties of Mentha L. plants. The field experiment was conducted at Aleksandras Stulginskis University (ASU) in 2017–2019, since 2019 at the Vytautas Magnus University Agricultural Academy Experimental Station, which is located in Ringaudai Eldership, Kaunas District (coordinates 54 ° 53′ 08.9″ N, 23° 50′ 08.02″ E). The effect of different concentrations of amino acid solutions on the chemical composition of mints depended on the mint variety. Spraying with all amino acids solutions significantly increased the dry matter, crude fiber and crude ash content in M. spicata ‘Crispa’ mints while a positive effect of amino acids solutions on the protein content was found only in M. piperita ‘Granada’ mints sprayed only with 200 mg l^–1 tyrosine solution, where the amount of protein increased significantly by 1.41-fold compared to that of non-sprayed plants. The intensity of the synthesis of photosynthetic pigments depended on the amino acid solutions used and the variety of mint. There were both inhibitory and stimulatory effects.