Regulation of nutrient-stress signaling through the plant vascular system

氮、磷、钾肥的应用使我们能够提高农业生产率。现代育种计划寻求发展作物品种，以提高养分利用效率，以实现作物的可持续产量，并在减少/限制化肥投入的情况下确保全球粮食安全。一旦植物面临矿质养分供应的限制，根通常是第一个对这些胁迫条件做出反应的组织，这些胁迫是由根定位的机制感受到的；根将这些胁迫转化为根衍生的信号，通过木质部传输，将具有挑战性的条件传达给地上部分。将这些信号传递到营养组织会产生特定的输出信号，这些信号进入韧皮部，将指令从茎带回根，整合发育和生理过程的需要。虽然文献中有明确的证据表明植物维管系统是有效的信息传递途径，但关于这些途径中的信号成分以及它们如何在矿质营养动态平衡中发挥作用，仍有许多有待发现。 我的研究计划的长期目标是验证营养胁迫信号的分子调控机制，这种机制是通过植物维管系统，特别是韧皮部的根冠通讯来调节的。为了进一步了解韧皮部在长距离营养胁迫信号传递中的作用，我在这里概述了一种策略，通过韧皮部介导的长距离信号分子来识别参与整合营养动态平衡的调控机制。目前有关韧皮部移动分子在营养胁迫信号传递中的作用的信息有限，将利用功能基因组学、生物信息学、生理和蛋白质生物化学研究来解决以下目标：1)确定哪些营养胁迫响应韧皮部蛋白运输到根部和顶端；2)确定哪些可移动转录因子在信号传递到库区组织的基因调控途径中起作用；3)验证这些已确定的韧皮部移动信号分子在植物对营养胁迫条件的发育适应反应中的作用。这项提案中描述的研究将增加对分子调控机制的理解和新的见解，分子调控机制在植物中由韧皮部系统介导的养分吸收和利用。这些知识将为旨在提高作物养分利用效率的育种计划提供潜在的基因靶点和基础。

Application of nitrogen/phosphorous/potassium fertilizers enables us to achieve enhanced productivity in agriculture. Modern breeding program has sought to develop crop species to increase nutrient use efficiency for achieving sustainable crop yield and ensuring global food security under reduced/limited fertilizer inputs. Once plants face limitations in mineral nutrient availability, roots are usually the first tissues to respond to these stress conditions which are sensed by root-localized mechanisms; the root translates these stresses into the root-derived signals that are transported through the xylem to communicate the challenging conditions to the shoot. Delivery of these signals to vegetative tissues elicits production of specific output signals that enter the phloem to carry commands from the shoot, back to the root, to integrate the requirements for developmental and physiological processes. Although there is clear evidence in the literature that the plant vascular system functions as the effective communication pathway, much remains to be discovered in terms of the signaling components in these pathways and how they function in mineral nutrient homeostasis. The long-term goal of my research program is to verify molecular regulatory mechanisms in nutrient-stress signaling, mediated by the root-shoot communication through the plant vascular system, especially the phloem. To advance the knowledge of the phloem function in long-distance nutrient-stress signaling, I outline here a strategy to identify regulatory mechanisms involved in integrating nutrient homeostasis by phloem-mediated long-distance signaling molecules. Limited information is available on the role of phloem mobile molecules in nutrient-stress signaling, and the utilization of functional genomics, bioinformatics, physiological and protein biochemistry studies will be involved to address the following objectives: 1) Determine which nutrient-stress responsive phloem proteins traffic to the root and shoot apex, 2) Characterize mobile transcription factors which function in gene regulatory pathways at the sites the signals are delivered to responsive sink tissues, 3) Validate the role of these identified phloem-mobile signaling molecules in plant developmental adaptive responses to nutrient-stress conditions. The studies described in this proposal will provide increased understanding and new insights into molecular regulatory mechanisms that serve in nutrient uptake and utilization in plants, mediated by phloem-based systems. This knowledge would offer potential gene targets and a basis for breeding programs aimed at enhancing nutrient use efficiency in crop plants.