Nitrogen (N) is quantitatively the most important nutrient that drives plant growth and productivity. However, application of N fertilisers in modern agriculture results in pollution, threatening environmental and human health. Leaching of N from crop soil jeopardises the quality of drinking water, and eutrophication of surface waters remains a pervasive problem globally. Furthermore, the potent greenhouse gas nitrous oxide (N2O) is emitted from N-fertilised agricultural soils and accounts for over 10% of the global greenhouse gas budget.
Inorganic forms of N, i.e. nitrate and ammonium, are considered the main source of N acquired by crops, but the preference of plant species for different N sources varies considerably. In soils of natural ecosystems N occurs in organic form (amino acids, peptides, protein, etc.), while inorganic N (nitrate, ammonium) dominates most agricultural soils. There is now much evidence that plants do not rely exclusively on inorganic N, but also take up organic N. Although plants use, and in some ecosystems depend on organic N, the contribution of organic N to the plant’s N budget is unclear due to the complex interactions between plants, microbes and soil with simultaneous conversions, uptake and release of N. Knowledge of the molecular-physiological mechanisms of N uptake, transport and assimilation is required to determine how plants use organic N in the context of soil and N supply.
Our research focuses on the role of peptides and peptide transporters for nitrogen acquisition and plant performance, and our previous studies contributed to the current understanding of the uptake and reallocation of peptides in plants. We now want to deepen this research by exploring trafficking pathways of peptide transporters to their target membrane, characterizing determinants for substrate selectivity, and isolating mutants and Arabidopsis accessions with altered regulation of peptide metabolism and transport.