FOR 1061: Dynamic Storage Functions of Plant Vacuoles During Cold and Osmotic Stress
Zusammenfassung der Projektergebnisse
At the beginning of the Research Group (FOR1061) our knowledge on the dynamic storage processes in plant mesophyll vacuoles was rather limited. Within the two funding periods we mainly focused on following aims: (i) we wished to identify the molecular nature of novel transport proteins involved in import or export of solutes (mostly sugars) across the vacuolar membrane. (ii) we wished to clarify the modes of transport catalyzed by these proteins in detail. (iii) we wished to decipher how the activity of these transporters is controlled on the post-translational level. (iv) we aimed to set the activity of corresponding transport proteins into the context of acclimation to cold temperatures and to plant (seed) yield. (v) we wished to clarify how energization of the vacuole by V-ATPase and V-PPiase is regulated and how these processes contribute to solute storage and organ development, and (vi) we aimed to describe cellular sorting process required to direct transporters into the vacuolar membrane. In the frame of FOR1061 we jointly cooperated and contributed significant findings to the open questions named above. We identified several so far unknown vacuolar sugar transport proteins on the molecular level. In addition, we demonstrated that the activity of the major sugar importer TMT is governed by the protein kinase VIK1 and we were able to reveal that vacuolar sugar homeostasis is critical for frost tolerance, as well as for total seed yield. Beside these findings, we analyzed in detail how vacuolar energetization is controlled by the two proton pumps V-ATPase and V-PPiase. These findings are complemented by an in depth analysis of cellular sorting mechanisms required for transport of hydrophobic membrane proteins into the tonoplast. Moreover, sophisticated methods have been developed and optimized (e.g. “whole vacuole recording” or phospho-proteomics on vacuolar membranes) in FOR 1061 opening future attempts to analyze transport processes across the tonoplast. In total we published so far 32 papers, filed two patents and continued our synergistic cooperation also in further coordinated research programs. In summary, we have the impression that work carried out in FOR1061 provided important scientific insight to understand the impact of vacuoles on cellular, organ and systemic levels.
