Multi-level characterization of the biostimulating effect of a protein hydrolysate

Humanity is facing a growing demand for food to feed an expanding population, while agricultural production takes place in an increasingly challenging environment. Global use of nitrogen and other mineral fertilisers in agriculture is therefore expected to increase by a further 60% by 2060. Yet, the proportion of mineral fertilisers, particularly nitrogen fertilisers, that crops effectively use remains relatively low: for example, only 40–60% of applied nitrogen is taken up by the crop. In addition to the pollution they generate, the production of nitrogen fertilisers is highly energy-intensive. Developing naturally derived molecules to improve fertilisation and protect crops against stress is therefore an important area of current research in agronomy.

In this context, the use of biostimulants is a promising agricultural strategy for maintaining crop yields while reducing reliance on mineral fertilisers. Protein hydrolysates are known to promote plant growth and yield, but the mechanisms underlying these effects remain poorly understood. To better identify and characterize the physiological and molecular targets of these biostimulants, their effects were investigated in the model species Arabidopsis thaliana.

The effects of protein hydrolysates on plant growth, resistance to biotic and abiotic stresses, and yield were assessed. The hydrolysate tested significantly stimulated the growth of Arabidopsis thaliana plants. In vitro, it increased primary root growth under nitrogen-rich conditions, demonstrating a genuine biostimulant effect rather than simply a nutritional effect. To better mimic field-grown conditions, experiments were also conducted using the Phenoscope, a robotic phenotyping platform that enables highly controlled growth. These experiments revealed a dose-dependent increase in shoot area and plant biomass following treatment with the hydrolysate.
The tested product altered the expression of numerous genes. These changes notably resulted in stimulation of nitrogen metabolism, together with reduced nitrate assimilation. In addition, the accumulation of numerous metabolites, including several amino acids, was observed. This accumulation is likely to underlie the increased activity of the TOR kinase, a central regulator of growth in all eukaryotes.

This work aims to optimise the use of biostimulants by improving our understanding of their modes of action. Ultimately, these findings should help improve nitrogen-use efficiency while reducing environmental impacts. Conducted as part of a CIFRE PhD project co-funded by Fertinagro France, this research could also pave the way for the development of new biostimulants.


Research developed at the Institute Jean-Pierre Bourgin for Plant Sciences in collaboration.