Live detection of secreted plant peptides

Excessive utilization of chemical fertilizers and growth enhancers in modern farming has become a key focus area for sustainable agriculture due to their negative environmental impact and there is an urgent demand for development of new sustainable growth enhancers. Plant growth promoting peptides (PGPP) are endogenous plant peptides that facilitate and enhance the growth of plants, e.g., by triggering growth of specific cells or stimulating nutrient uptake. These peptides could potentially be utilized as biological growth enhancers, under the concept of ‘biologicals’. Examples of PGPPs are the tyrosine-sulfated peptides PSK (Phytosulfokine) and PSY1 (plant peptide containing tyrosine sulfation).

Addition of these peptides to plant growth media increases growth when tested on a petri-dish scale. The effect has so far not been fully exploited in a larger scale due to the chemical complexity of the peptides. They are difficult to characterize because they act like paracrine signalling molecules, by being present in nanomolar concentrations and able to move over long distances. However, the huge growth promoting potential of these small peptides relies to a large extent on the understanding of their mode of action. This is best studied in a system mimicking its natural conditions, but until now studies of these peptides have been restricted to biochemical and recombinant protein analyses, due to their elusive nature, and knowledge of their action under natural conditions has remained limited.

We are developing a peptide-receptor sensing system for live imaging of the specific perception mechanisms for the PSY and PSK peptides, which requires knowledge about their target site and signalling.