Project

Discipline

accession; Arabidopsis thaliana; plasma membrane; tonoplast; mutant; transport; organic nitrogen; peptide

Lead
Stickstoff ist für Wachstum und Ertrag von Pflanzen essentiell und wird Kulturpflanzen in der Regel in Form von Dünger zugeführt. Die ineffiziente Nutzung von anorganischem Stickstoff kann zu dessen Auswaschung und damit unter anderem zu Beeinträchtigungen anderer Ökosysteme führen. Die Pflanze kann auch organische Stickstoffverbindungen nutzen. Inwieweit letztere zur Pflanzenernährung beitragen ist jedoch immer noch wenig erforscht und Gegenstand wissenschaftlicher Diskussionen.
Lay summary
Unsere Forschung hat zum Ziel die Aufnahme und Verteilung von organischem Stickstoff in Pflanzen besser zu verstehen. Insbesondere interessiert uns die Aufnahme und der Metabolismus kleiner Peptide. Im Projekt versuchen wir Arabidopsis-Mutanten zu identifizieren, die ein verbessertes oder eingeschränktes Wachstum auf Peptiden als Stickstoffquelle aufweisen, um Transporter, Regulatoren und Enzyme zu identifizieren, die an der effizienten Nutzung von organischem Stickstoff beteiligt sind. Neben diesem generellen Ansatz untersuchen wir andererseits den Beitrag von Peptidtransportern für die Stickstoffversorgung der Pflanzen und charakterisieren die beteiligten Transportproteine.   Detaillierte Kenntnisse zur Aufnahme und Verteilung von organischem Stickstoff und dessen Transport in Ernteprodukte wie beispielsweise Samen tragen zur Klärung der Rolle von organischem Stickstoff für die Produktivität der Pflanzen bei. Erkenntnisse aus diesen Arbeiten können möglicherweise in der Pflanzenzüchtung und für eine nachhaltige Landwirtschaft genutzt werden.

Direct link to Lay Summary

Last update: 20.12.2013

Lead
Nitrogen (N) is limiting plant growth and reproduction. While inorganic N represents the largest pool of soluble N in many fertilized soils, organic N forms, including amino acids, peptides and proteins, often dominate non-fertilized soils. There is increasing evidence that in addition to inorganic N, plants also acquire organic N. It remains however unclear, how much the direct uptake of organic N contributes to plant N needs.
Lay summary
Aim of the project Our research has contributed to the current understanding of the uptake and reallocation of amino acids and peptides in plants. In our current work, we aim to deepen this research by exploring peptide transporter function and regulation, as well as peptide metabolism. The interest in organic N as plant N sources is driven by a need for sustainable agricultural practices. Inorganic N dominated, fertilized soils lose N and cause pollution of the environment, as well as a carrying a large energy footprint of synthetic N fertilizer manufactures. Increased understanding on organic N uptake and distribution for plant productivity and growth, may contribute to improve future plant breeding and sustainable agriculture.

Direct link to Lay Summary

Last update: 20.12.2013

Active participation

Self-organised

Number	Title	Start	Funding scheme

Nitrogen (N) is limiting plant growth and reproduction. N uptake from the soil, its assimilation and subsequent reallocation are therefore key processes driving primary productivity of plants. While inorganic N (nitrate and ammonium) represents the largest pool of soluble N in many fertilized soils, organic N forms, including amino acids, peptides and proteins (soluble and bound to the soil matrix), often dominate non-fertilized soils. It is generally assumed that plants use predominantly inorganic N, but there is increasing evidence that plants also acquire organic N from the soil. It remains however unclear, how much the direct uptake of organic N contributes to plant N needs. The interest in organic N as plant N sources is driven by a need for sustainable agricultural practices. Inorganic N dominated, fertilized soils lose N and cause pollution of hydrosphere, atmosphere and pedosphere, as well as a carrying a large energy footprint of synthetic N fertilizer manufactures.Our research has contributed considerably to the current understanding of the uptake and reallocation of peptides in plants. We were first to determine the selectivity and affinities of di/tripeptide transporters, their expression and intracellular localization, and have identified structural determinants required for their delivery to the tonoplast or plasma membrane. We recently isolated, in a low-scale forward genetic screen, several mutants with reduced growth on dipeptides as N source, and identified Arabidopsis accessions with altered performance on organic N.Here, we aim to deepen this research by exploring the trafficking pathways of peptide transporters to their destination membranes and by identifying determinants (i.e. amino acids or domains) important for substrate recognition. We will perform a large-scale genetic screen to search for new mutants, and use already isolated mutants and Arabidopsis accessions to identify and characterize novel genes involved in peptide use. The project will generate (i) fundamental information on the function of peptide transporters, and (ii) provide knowledge on regulation and organic N use in an ecological context. The objectives of the proposed project are to:(i)identify trafficking pathways of peptide transporters to their target membrane(ii)characterize determinants required for substrate selectivity (iii)isolate mutants in a genetic screen with peptides as N sources and characterize mutants to identify novel loci important for function or regulation of peptide metabolism and transport. (iv) explore the of natural genetic variation of Arabidopsis for performance on organic N Our group is very well positioned to perform this research with all required knowledge and materials available for rapid advancement. Heterologous expression systems (yeast and oocytes) for analysis of substrate selectivity, and localization of GFP/fusion proteins for exploring the trafficking pathways, are well established. We will hit the ground running with several mutants and accessions with altered growth on peptides as N source that we have already identified. Knowledge generated in the proposed research will provide a deeper understanding of peptide transporter function and regulation and will advance information on membrane protein trafficking and organic N use. Increased understanding on organic N uptake and distribution for plant productivity and growth, may contribute to improve future plant breeding and sustainable agriculture.