Collaborative Research: Competing Sinks as Constraints on Plant Defense Responses

智慧植物通常通过激活复杂的防御反应来应对害虫和病原体的攻击，其中包括产生有毒或威慑化学物质。然而，所有的植物组织对攻击的反应并不相同。在自然界中，提供抗病虫害和提高收获质量的植物防御系统的分布是不均匀的，而且众所周知很难预测。最近，人们发现了激活防御反应的关键第一步。在杨树中，研究表明，受伤组织必须通过植物维管系统输入资源，在这种情况下，糖，以支持防御物质的生产。在这些树中，受伤的组织改变了它们的新陈代谢，变得更强大的“糖槽”，并从植物的其他地方吸取资源。因此，更强的糖库有更强的防御反应，当糖流中断时，这种防御反应就会消失。这一观察结果有助于解释为什么植物防御系统在自然界中分布不均。它还提出了几种控制植物产品水平的策略，包括那些来自农业上重要物种的产品。该项目将确定伤害是否会增强其他植物物种和类型的“糖库”强度，包括产生各种防御物质的草本植物和藤本植物，如单宁、生物碱、蛋白质和硫代葡萄糖酸盐。该项目涉及大规模实验，以测试许多不同植物改变糖和其他资源的长距离流动以应对攻击的假设。它还将研究可能扰乱自然界糖分流动的因素，例如花和水果的发育，这些花朵和水果的发育超过了受损组织对糖资源的竞争，或者多种昆虫或病原体的同时攻击。更广泛的影响这些研究的结果将提供对影响植物抗虫性的因素的洞察，并可能被操纵以提高作物或树木的生产力。植物用来操纵糖流的策略在农业中很重要，因为它们决定了生产和收获的时机和质量。所研究的机制也是植物固碳和碳释放的核心，并可能影响全球碳预算。结果应该决定是否可以改变像杨树这样的树木来在地下封存额外的碳。该项目将使来自两个不同(大/小)机构的大量本科生参与跨学科、合作研究和外联活动(包括K-12学校)。

INTELLECTUAL MERITPlants often respond to attack by pests and pathogens by activating complex defense responses, which include the production of toxic or deterrent chemicals. However, all plant tissues are not equally responsive to attack. In nature the distribution of plant defenses, which provide pest and pathogen resistance and enhance harvest quality, is uneven and notoriously difficult to predict. Recently, a critical first step in the activation of defense responses was discovered. In poplar trees, it was shown that wounded tissues must import resources, in this case sugars, via the plant vascular system to support the production of defensive substances. In these trees, wounded tissues alter their metabolism, becoming stronger "sugar sinks" and drawing resources away from elsewhere in the plant. As a result, stronger sugar sinks have stronger defense responses which disappear whenever the flow of sugars is interrupted. This observation helps to explain why plant defenses are unevenly distributed in nature. It also suggests several strategies for manipulating levels of plant products, including those from agriculturally-important species. This project would determine if wounding boosts the "sugar sink" strength of other plant species and types, including herbs and vines producing a wide variety of defensive substances such as tannins, alkaloids, proteins, and glucosinolates. The project involves large-scale experiments to test the hypothesis that many different plants shift the long-distance flow of sugars and other resources in response to attack. It will also examine factors that would disrupt sugar flow in nature, such as the development of flowers and fruits which out-compete wounded tissues for sugar resources or the simultaneous attack by multiple insects or pathogens. BROADER IMPACTS Results of these studies will provide insight into factors that influence pest resistance of plants and may be manipulated to enhance crop or tree productivity. The strategies plants use to manipulate sugar flow are important in agriculture, since they determine both the timing and quality of production and harvest. The mechanisms studied are also central to carbon sequestration and release by plants and may impinge on the global carbon budget. Results should determine whether trees like poplar can be altered to sequester additional carbon belowground. The project will engage a substantial number of undergraduates from two contrasting (large/small) institutions in interdisciplinary, collaborative research and outreach (including K-12 schools).