Collaborative Research: Coordinate Induction of Sink Strength and Polyphenol Metabolism in Trees

植物对害虫和病原体损害作出反应的能力很普遍，但并非所有植物组织都能产生防御反应。 幼叶的防御反应能力最强，但随着年龄的增长而急剧下降。 植物不同部位防御能力的差异影响着食草动物在植物上的觅食、食草动物对植物防御产生抵抗力的能力以及捕食者成功定位食草动物的能力。为了了解植物的生态和进化及其与食草动物的相互作用，了解不同植物组织之间植物防御反应的差异至关重要。 碳水化合物在树冠中的移动可能会影响幼叶发展防御反应的能力。 例如，受伤的杨树叶获取生产防御性化学物质（多酚类物质）所需资源的能力似乎受到从植物维管系统输入碳水化合物的速度的影响。 换句话说，防御反应的大小与流向受伤叶子的资源直接相关。 这种资源流动会导致不同植物组织之间的防御反应发生变化，因为受伤的组织从植物维管系统获取资源的能力有所不同。 PI 提议通过温室和实验室实验对杨树和橡树杂交树苗进行严格检验。 将进行植物叶子的化学分析以评估防御反应，并使用碳 13 标记实验来测量整个植物的资源移动速率。 拟议的研究将导致（1）开发一个模型，旨在预测防御反应可能发生的地点和时间，（2）建立可广泛应用于现场植物群落的监测技术，以及（3）对研究生和本科生进行植物科学方面的培训。

The ability of plants to respond to damage by pests and pathogens is widespread, but not all plant tissues are capable of producing defensive responses. Defensive responsiveness is greatest in young leaves and decreases dramatically with age. The variation in defensive capabilities among different parts of plants affects the foraging of herbivores on plants, the ability of herbivores to develop resistance to plant defenses, and the success of predators in locating herbivores. To understand the ecology and evolution of plants and their interactions with herbivores, it is critical to understand how plant defensive responses differ among different plant tissues. The movement of carbohydrates throughout the canopies of trees may influence the ability of young foliage to develop defensive responses. For example, the ability of wounded Poplar leaves to obtain the resources they need to produce defensive chemicals (polyphenolics) appears to be affected by the rate at which carbohydrates are imported from the plant vascular system. In other words, the magnitude of the defensive response is directly related to the flow of resources to wounded leaves. This flow of resources causes variation in defensive responses among different plant tissues, because wounded tissues vary in their ability to acquire resources from the plant vascular system. The PIs propose to test this hypothesis rigorously with greenhouse and laboratory experiments on hybrid poplar and oak saplings. Chemical analyses of plant foliage will be conducted to assess defensive responses, and carbon 13 labeling experiments will be used to measure rates of resource movement in whole plants. The proposed research will result in (1) the development of a model designed to predict where and when defensive responses are likely to occur, (2) the establishment of monitoring technology that can be applied to a broad range of plant communities in the field, and (3) the training of graduate and undergraduate students in the plant sciences.