GENOME-WIDE TRANSCRIPTIONAL CHANGES INDUCED IN MAIZE ROOTS IN RESPONSE TO PROTEIN HYDROLYSATES AND FREE AMINO ACIDS

Agricultural biostimulants include a variety of formulations aiming at improving nutrient assimilation, enhancing crop productivity and mitigating biotic and abiotic stress. Biostimulants based on protein hydrolysates typically consist of a mixture of peptides and free amino acids derived from the hydrolysis of plant or animal sources. The present work represents the first attempt to dissect the effects and the action mechanisms of a protein hydrolysate derived from animal residues in comparison with the effects induced by free amino acids supply on maize root growth. The application of the protein hydrolysate was more effective than amino acids mixture in root growth promotion. The transcriptomic analysis allowed evidencing common and treatment-specific effects of protein hydrolysate and amino acids primarily on transport processes, hormone metabolism and stress responses. The free amino acids treatment induced a stronger transcriptional modification than the protein hydrolysate, particularly on stress-related genes. Both biostimulants modulated transcripts involved in inorganic nitrogen uptake and oligopeptide transport, but also influenced transcripts involved in gibberellin metabolism and in auxin signalling. Moreover, protein hydrolysates displayed specific effects on cytokinins and jasmonate metabolism.