Reassessing the Biological Functions of the Plant Type I H+-PPase

植物利用水和来自阳光的能量来制造能量密集型糖。在叶片中产生糖后，需要将糖转移到植物的其他部分，在那里消耗这些能量。这些消耗的组织被称为“水槽”。与我们的循环系统类似，植物有一个叫做韧皮部的细胞网络，它允许糖从来源(叶子)移动到下沉组织。长期以来，科学家一直寻求通过调节糖的运动来提高农作物的产量，其理论是，如果供应增加，产量就可以增加，而昂贵的、对环境有问题的化肥的投入就会减少。以前的工作已经确定了韧皮部中的一个转运体，本提案旨在描述这一关键调控因子在糖运输中的功能。明确这种转运体如何将糖转移到植物内的各种组织中，将使科学家能够开发出优化作物中糖运输的策略，从而在增加产量的同时减少生产农业对环境的影响。该项目首席科学家的拉美裔血统使该团队在吸引拉美裔观众方面具有优势，方法是用西班牙语传播复杂的科学主题，以点燃普通公众和学生对科学的兴趣。参与该项目的科学家将组织一次关于农业生物技术与社会的国际会议，并将开发基于网络的双语教学工具，以促进科学素养。光同化物在其生产和利用地点的分配是植物生长和发育的关键决定因素。新的证据表明，光同化物分配的调节部分是由I型H+-PPase介导的。这种转运蛋白在液泡膜上的作用已经确定；然而，最近的工作表明这种转运蛋白的质膜(PM)定位，并证实它在韧皮部伴生细胞(CC)中显著表达，从而扰乱了这一排他性功能。研究人员提出，这种酶有两个相反的作用，PPI的水解和合成，这两个作用有助于一系列为植物生长提供能量的事件。他们将测试拟南芥H+-PPase在异源系统(酿酒酵母)和植物中合成PPI的能力。同时，一系列的遗传学、免疫组织化学和生理学实验将确定这个泵如何影响同化物的分配。这项基础研究将H+-PPase归类为参与光合作用产物分配和代谢的中心介体。

Plants use water and the energy from sunlight to make energy-dense sugars. After production in the leaves, the sugar needs to be moved to other parts of the plant where this energy is consumed. These consuming tissues are termed 'sinks'. Analogous to our circulatory systems, plants have a network of cells called the phloem that allow the movement of sugars from source (leaves) to the sink tissues. Scientists have long sought to increase the yield of crops by regulating the movement of sugars, the theory being that if supplies are increased, yield can be increased while the input of costly and environmentally problematic fertilizers is diminished. Previous work has identified a transporter within the phloem and this proposal aims to characterize the function of this key regulator in sugar transport. Specifying how this transporter moves sugar to various tissues within the plant will allow scientists to develop strategies to optimize sugar translocation in crops that increase yield while reducing the environmental impacts of production agriculture. The Hispanic roots of the lead scientist for this project give this team an edge in engaging Hispanic audiences by communicating complex scientific topics in Spanish to ignite interest in science among the general public and among students. The scientists involved in this project will organize an international meeting on agricultural biotechnology and society, and will also develop bilingual web-based teaching tools to promote scientific literacy.The partitioning of photoassimilates between their sites of production and utilization is a key determinant of plant growth and development. Emerging evidence suggests regulation of photoassimilate partitioning is mediated in part by a type I H+-PPase. A role for this transporter has been established at the tonoplast; however, this exclusive function has been unsettled by recent work showing plasma membrane (PM) localization of this transporter and establishing that it is prominently expressed in phloem companion cells (CC). The researchers propose this enzyme has two opposing roles, PPi hydrolysis and synthesis that contribute to a cascade of events that energize plant growth. They will test the capacity of the Arabidopsis thaliana H+-PPase to synthetize PPi in a heterologous system (Saccharomyces cerevisiae) and in plants. Concurrently, a series of genetic, immunohistochemical and physiological experiments will determine how this pump affects the partitioning of assimilates. This fundamental research will catalog that H+-PPases as a central mediator involved in the allocation and metabolism of photosynthates.