Cross-talk between redox, metabolic and hormonal retrograde chloroplast signals in the expressional regulation of nuclear encoded plastid proteins

基于调控动力学和相关转录因子的结果，以及第一个资助期确定的方法，第二阶段的工作计划侧重于描述代谢调节逆行信号的早期事件，特别是在轻度变化期间。(I)在荷尔蒙、氧化还原和代谢物过程中存在缺陷的野生型和定义突变体中的时间分辨转录反应将用于处理信号和代谢网络的组成部分。(Ii)逆行信号依赖于组合信号整合，例如，几种转录因子转录水平依赖于光、二氧化碳和脱落酸。因此，该项目将研究光合作用相关的氧化还原、脱落酸和代谢物信号的组合效应，以确定信号层次和整合。(Iii)已确定的AP2/EREBP家族快速反应转录调控因子和NAC转录因子的功能将在体外和体内进行研究。(Iv)转录积累和蛋白质数量之间的差异表明，转录后调控最有可能受到逆行信号的控制，这些逆行信号将使用标记有标志表位的核糖体蛋白L18拟南芥品系来比较总的和核糖体结合的mRNA。这将补充我们在转录后水平上破译氧化还原、脱落酸和代谢物信号在逆行信号中的组合效应的努力。

Based on the results on regulatory dynamics and involved transcription factors, and also on methods established in the first funding period, the work plan for the second period focuses on characterizing early events in retrograde signaling for metabolic adjustment, particularly during light shift. (i) Time-resolved transcriptional responses in wild type and defined mutants with defects in hormonal, redox and metabolite processes will be used to address components of the signaling and metabolic network. (ii) Retrograde signaling relies on combinatorial signal integration as seen e.g. for several transcription factor transcript level in dependence on light, CO2 and abscisic acid. Thus, the project will investigate the combinatorial effect of photosynthesis-related redox, abscisic acid and metabolite signals in order to define the signaling hierarchy and integration. (iii) The function of identified very fast responding transcriptional regulators of the AP2/EREBP family and a NAC transcription factor will be studied in vitro and in vivo. (iv) Discrepancies between transcript accumulation and protein amounts indicate posttranscriptional regulation being most likely under control of retrograde signals that will be addressed using FLAG-epitope tagged ribosomal protein L18 Arabidopsis lines to compare total and ribosome-bound mRNA. This will complement our attempt to decipher the combinatorial effect of redox, abscisic acid and metabolite cues in retrograde signaling at the posttranscriptional level.