Regulation and function of Arabidopsis UMAMIT amino acid transport facilitators in response to dark-induced energy starvation

• Applicant: Professor Dr. Wolfgang Dröge-Laser
• Subject Area: Plant Genetics and Genomics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426670491

In plants, nutrients like carbohydrates and amino acids (aa) need to be allocated between source and sink tissues to assure sufficient supply and consequently survival. Particularly in response to energy limiting conditions, a tight co-ordination of energy homeostasis and nutrient allocation is required. Recently, we defined the Snf1 RELATED KINASE1 (SnRK1) and the down-stream network of C/S1 basic leucine zipper (bZIP) transcription factors controlling aa catabolism to sustain mitochondrial ATP synthesis during dark-induced senescence (DIS). In this project, we aim at linking SnRK1-C/S1-bZIP signalling to the USUALLY MULTIPLE AMINO ACIDS MOVE IN AND OUT TRANSPORTERS (UMAMITs), which perform as aa facilitators in plants. Being transcriptionally induced during DIS, and localized in the tonoplast, we propose that UMAMIT33 is involved in intracellular aa allocation. Hence, this project studies the cellular localization of UMAMIT33, its expression patterns, transporter physiology and transcriptional regulation by SnRK1-C/S1-bZIP-signalling. To gain insight into its function, loss-of-function plants will be analysed for phenotypical and molecular DIS responses, cellular aa distribution and aa export from the dark-treated leaves. As exemplified for UMAMIT33, we will study 1-2 further S1-bZIP regulated UMAMITs in DIS, selected by an unbiased transcriptome study. The latter approach will also provide a comprehensive overview of transporters from other families co-ordinated by the SnRK1-C/S1 bZIP low energy network. As nutrient allocation during stress significantly influence agronomical important properties such as yield and post-harvest shelf-life, the insights gained by this basic research may provide novel strategies for future crop improvement.

• DFG Programme: Research Grants