The meristematic regulatory network controlling the floral transition (BLOOM-NET)

本项目的总体目标是确定在茎尖分生组织（SAM）中调节开花时间的复杂调控网络，并模拟花过渡过程中该网络的定量和动态变化。近年来，通过遗传分析已经发现了几个在这一过程中起主要作用的蛋白。然而，精确的相互作用和时间行为，以及支撑这一监管体系稳健性的组成部分的特征，尚未被定义。这些信息对于预测突变或环境变化对开花时间的影响至关重要。最终，它将允许调整具有重要经济意义的作物的开花时间，并确保在需要时进行这种过渡。我们将重点关注MADS盒子转录因子（TFs）的一个子集，这些转录因子已被证明是模式物种拟南芥（Arabidopsis thaliana）成花转变的关键调节因子。开花的确切时间是由这些转录激活因子和抑制因子之间的紧密平衡调节的。我们的目标是进行湿实验室实验和建模的迭代循环，以获得全面和定量的数据集，从而得出新颖和可测试的假设。从湿法实验中获得的定量信息将被整合到一个简单的接线图中，该接线图描述了开花系统主要调控成分之间所有已知的定性相互作用。在项目结束时，这将导致一个描述分生组织中控制开花时间的调节步骤的数学模型。-确定在标准和扰动条件下茎尖分生组织（SAM）中关键调节因子（MADS蛋白）随时间的浓度，并将其与表型输出（即开花时间）联系起来。-使用新的ChIP-SEQ方法获得各种mads因子的综合结合位点数据集（即靶基因）。-获得野生型（WT）和突变型植物在向生殖发育过渡前后的各个时间点的分生组织时间转录组，并将这些数据与tf的直接靶点进行比较。-确定MADS盒TF分子的二聚化亲和力。在基因组水平预测靶位点，并模拟靶位点结合亲和力和mads因子二聚化亲和力。-将网络组成部分的定量和定性方面整合到一个数学模型中，该模型预测开花时间作为抑制因子和激活因子之间平衡的函数。

The overall aim of this project is to define the complex regulatory network that acts in the shoot apical meristem (SAM) to regulate the timing of transition to flowering, and to model quantitative and dynamic changes in this network during the floral transition.Several proteins with major functions in this process have been elucidated by genetic analyses in recent years. Nevertheless, the precise interplay and temporal behaviour, as well as the characteristics of the components that underpin the robustness of this regulatory system, have not been defined yet. This information is essential to predict the effects of mutations or environmental changes on flowering time. Ultimately, it will allow the adjustment of flowering time in crops of economic importance, and ensures that this transition occurs when required. We will focus on a sub-set of MADS box transcription factors (TFs) that have been shown to be the key regulators of the floral transition in the model species Arabidopsis thaliana. The exact timing of flowering is regulated by a tight balance between these transcriptional activators and suppressors. Our aim is to perform iterative cycles of wetlab experiments and modelling, to obtain comprehensive and quantitative data sets that lead to novel and testable hypotheses. Quantitative information derived from the wet experiments will be integrated in a simple wiring diagram describing all known qualitative interactions between the major regulatory components of the flowering system. Towards the end of the project this will lead to a mathematical model describing the regulatory steps controlling flowering time in the meristem. The following specific objectives are postulated:- Determine the concentrations of key-regulators (MADS proteins) in the shoot apical meristem (SAM) over time and link this to phenotypic output (i.e. the flowering time) under standard and perturbed conditions.- Obtain comprehensive binding site data-sets (i.e. target genes) of the various MADS-factors using a novel ChIP-SEQ approach.- Obtain the temporal transcriptome from the meristem of wild-type (WT) and mutant plants at various time points before and directly after the transition to reproductive development, and compare these data with the direct targets of TFs.- Determine the dimerization affinities of the MADS box TF molecules. Predict target sites at the genome level and model target site binding affinity and MADSfactor dimerization affinities.- Integrate the quantitative and qualitative aspects of the components of the network in a mathematical model that predicts the time of flowering as a function of balances between suppressors and activators.