Integrated Studies on the Phloem as a Long-Distance Communication System in Plants

生物系统利用复杂的控制网络来协调其细胞、发育和生理程序背后的复杂过程。在植物界，进化出独特的器官间交流系统。植物体内的信号通过木质部导管细胞和韧皮部筛管系统传递信息分子，木质部导管细胞成熟时死亡。这种维管网络的进化反映了需要将成熟器官感受到的环境输入(非生物和生物)传递到植物的分生组织区域。这种远程信号系统的一个重要结果是，新形成的器官可以发展出适合它们出现、成熟和发挥功能的环境的特性。这项建议描述了旨在进一步表征韧皮部在长距离信号传递中的作用的实验。为此，南瓜将被用作收集韧皮部汁液的模式植物，这些汁液将通过质谱学和生物信息学方法进行分析，以确定存在于高等植物易位溪流中的蛋白质种群。对韧皮部蛋白质组的分析，包括存在于易位流中的蛋白质，将对在被子植物独特的去核筛管系统中运行的代谢和信号通路的光谱产生新的见解。长期目标是确定(A)维持去核筛管系统和(B)整合植物遥远器官之间的发育和生理过程的途径。这些研究的结果应该会为植物界从单细胞进化到复杂的超细胞生物体所采取的路径提供新的视角。最后，这种韧皮部蛋白质组的长期影响将通过开发对植物过程的新控制来实现，包括在植物不同器官之间分享营养的方式。这种应用很可能在农业和动物/人类营养/健康方面产生重大影响。

Biological systems utilize sophisticated control networks to orchestrate complex processes underlying their cellular, developmental and physiological programs. In the plant kingdom, unique systems evolved for inter-organ communication. Signaling around the body of the plant occurs by delivery of information molecules via the xylem tracheary cells, which are dead at maturity, and the phloem sieve tube system. The evolution of this vascular network reflects, among other things, the need to communicate environmental inputs (abiotic and biotic), sensed by mature organs, to meristematic regions of the plant. An important consequence of this long-distance signaling system is that newly forming organs can develop properties optimized for the environment into which they will emerge, mature and function. This proposal describes experiments aimed at further characterizing the role of the phloem in long-distance signaling. To this end, pumpkin will be used as a model plant to collect phloem sap that will be analyzed by mass spectrometry and bioinformatics methods to identify the population of proteins that are present in the higher plant translocation stream. Analysis of the phloem proteome, comprising the proteins present in the translocation stream, will yield novel insights into the spectrum of metabolic and signaling pathways that operate within the unique enucleate sieve tube system of the angiosperms. Long term goals are to identify the pathways that (a) maintain the enucleate sieve tube system and (b) integrate developmental and physiological processes between distantly located organs of the plant. The results from these studies should provide new perspectives on the path taken by the plant kingdom during its evolution from single cells to complex, supracellular, organisms. Finally, the long-term impact of this phloem proteome will be through the development of new controls over plant processes, including the way nutrients are shared between the various plant organs. Such applications could well have major ramifications in terms of agriculture and animal/human nutrition/health.