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

在植物中，碳水化合物和氨基酸（aa）等营养物质需要在源和库组织之间分配，以确保充足的供应，从而生存。特别是在应对能量限制条件时，需要能量稳态和营养分配的紧密协调。最近，我们定义了Snf 1相关激酶1（SnRK 1）和下游网络的C/S1碱性亮氨酸拉链（bZIP）转录因子控制aa catalysts维持线粒体ATP合成在黑暗诱导衰老（DIS）。在这个项目中，我们的目标是将SnRK 1-C/S1-bZIP信号传导与通常的多氨基酸移入和移出转运体（UMAMIT）联系起来，UMAMIT在植物中作为aa促进剂。在DIS过程中被转录诱导，并定位于液泡膜中，我们建议UMAMIT 33参与细胞内aa分配。因此，本项目研究了UMAMIT 33的细胞定位，其表达模式，转运蛋白生理学和SnRK 1-C/S1-bZIP信号转导的转录调控。为了深入了解其功能，将分析功能丧失的植物的表型和分子DIS响应、细胞aa分布和来自黑暗处理的叶片的aa输出。作为UMAMIT 33的例子，我们将研究DIS中1-2个进一步的S1-bZIP调节的UMAMITs，通过无偏转录组研究选择。后一种方法还将提供由SnRK 1-C/S1 bZIP低能量网络协调的来自其他家庭的转运蛋白的全面概述。由于胁迫期间的养分分配显著影响重要的农艺性状，如产量和收获后货架期，这项基础研究所获得的见解可能为未来的作物改良提供新的策略。

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.