Understanding the effect of amino acids based biostimulant by an enantiomeric analysis of their active principles and a proteomic profiling approach

Plant biostimulants are products that contain multiple compounds and claim to activate a wide range of plant responses. Amino acid based products are one example of biostimulants with a complex composition and different product characteristics depending on their sources and production processes. Amino acid biostimulants are obtained mainly by chemical or enzymatic protein hydrolysis and the type of hydrolysis determine the content of free amino acids and their enantiomeric purity. While L-amino acids are biologically active, the application of D-amino acids has even shown deleterious. With the aim to highlight different quality compositions of amino acid biostimulants a comprehensive chiral analysis of different types of hydrolyzed protein biostimulants was performed. Results confirmed the high purity in L-amino acids in products obtained by enzymatic hydrolysis as well as a high racemization rate for those obtained through a chemical hydrolysis. Furthermore the application of the commercial biostimulant Terra-Sorb (R) Foliar with L-amino acids shows multiple agronomic effects such as the improvement of the photosynthetic process and the enhancement of crop tolerance to stress. A proteomic approach in wheat plants was undertaken in order to understand which molecular mechanisms are involved in the stimulating effect of the product. The improvement of wheat productivity seems to be mediated by a combination of an enhanced CO2 fixation, a more active protein metabolism and a decrease of oxidative stress.