COLLABORATIVE RESEARCH: Coordinate Induction of Sink Strength and Polyphenol Metabolism in Trees

植物对病虫害的反应能力是普遍存在的，但并不是所有的植物组织都能产生防御反应。防御反应在幼叶中最强，并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食草动物对植物的觅食，影响食草动物对植物防御的抵抗力，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的植物防御反应是至关重要的。碳水化合物在树冠上的移动可能会影响幼叶产生防御反应的能力。例如，受伤的杨树叶片获得产生防御性化学物质(多酚)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，防御反应的大小与资源流向伤叶直接相关。这种资源流动导致不同植物组织之间的防御反应不同，因为受伤组织从植物维管系统获得资源的能力不同。PI建议通过温室和实验室对杨树和橡树的杂交树苗进行严格的实验来检验这个假设。将对植物叶片进行化学分析，以评估防御反应，并将使用碳13标记实验来测量整个植物的资源移动速度。这项拟议的研究将导致(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)建立可应用于田间广泛植物群落的监测技术，以及(3)培训植物科学方面的研究生和本科生。

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.