Collaborative Research: Using herbivore kairomones to assess short-term and legacy risk responses in the early life stages of long-lived woody plants

即使植物不能移动，它们也远非对食草动物毫无防备。虽然探索植物如何保护自己的研究主要集中在响应食草动物攻击而发生的植物防御变化上，但最近已经表明，植物甚至可以在攻击开始之前检测和响应食草动物的线索（称为“利它素”）。蜗牛和蛞蝓的粘液，攻击种子和幼苗的食草动物，触发幼苗的防御反应，帮助植物在蛞蝓或其他食草动物的后续攻击中幸存下来。这种防御可能对幼苗糖枫树特别重要，糖枫树是美国东北部的一种标志性树木，对枫糖工业至关重要，在其整个范围内都在下降。一种侵入性的鼻涕虫，dusky Arion，对新发芽的糖枫树幼苗构成了重大威胁;该项目讨论了这种鼻涕虫的粘液如何影响从幼苗到树苗的糖枫树的抗草食动物防御。它还评估了生命早期接触粘液是否有助于保护糖枫免受后来到达的食草动物的侵害，从吉普赛蛾到白尾鹿。该项目还资助了罗德岛科学和数学研究性学习（SMILE）计划的工作，该计划是一个以课堂为基础的组织，与4-12年级的孩子合作，以增加从高中毕业准备进入高等教育并追求STEM职业的教育弱势学生的数量。学生与项目科学家合作进行实地和课堂体验，采用基于探究的学习来揭示生态学原理并探索当地生态系统。尽管大量研究探索了食草动物攻击期间和之后的植物防御诱导，关于植物是否以及如何利用诸如利它素之类的攻击前线索，（食草动物释放的化学物质与攻击无关，被植物检测到，从而为植物提供益处），以先发制人地诱导防御。食草动物利它素最近已被记录在多个系统中;蛞蝓/蜗牛粘液，一种容易获得和可操纵的利它素，可用于询问有关植物风险感知和诱导反应的新问题。鼻涕虫优先攻击幼苗，一个非常脆弱的生活史阶段，突出了攻击前粘液检测和响应的选择性优势。在长寿命木本植物系统中，以下问题得到解决：不同的风险线索如何影响不同年龄幼苗的生长和防御？个体发生的易感性变化如何决定反应模式？风险认知和个体发育在该领域的直接和遗留后果是什么？这些问题是使用蛞蝓阿里翁subfuscus和糖枫Acer saccharum在实验中探索风险线索质量和苗龄之间的相互作用，在短期（~1个月）和长期（1年）。时间段.这是第一个关于利它素如何影响木本植物防御、生长和随后的草食动物脆弱性的研究。操纵草食动物的线索，个体发育，和不同的易感性内和跨季节探讨当前的植物防御是否反映了“草食动物风险过去的幽灵”;现在的防御可能往往只有考虑到过去的信息由plants接收有意义。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Even though plants cannot move, they are far from defenseless against their herbivores. While research exploring how plants protect themselves has focused largely on changes in plant defense that occur in response to herbivore attack, it has recently been shown that plants can detect and respond to herbivore cues (referred to as ‘kairomones’) even before an attack begins. Mucus from snails and slugs, herbivores that attack seeds and seedlings, triggers defensive responses in seedlings that help the plants survive subsequent attack by slugs or other herbivores. Such defenses may be particularly important for seedling sugar maple trees, an iconic tree in the northeastern US critical to the maple sugar industry that is declining throughout its range. An invasive slug, the dusky Arion, poses a major threat to newly germinated sugar maple seedlings; this project addresses how mucus from this slug affects the anti-herbivore defenses of sugar maples ranging in age from seedlings to saplings. It also evaluates whether early-life exposure to mucus can help protect sugar maples against later-arriving herbivores ranging from gypsy moths to white-tailed deer. The project also funds work by the Rhode Island-based Science and Math Investigative Learning (SMILE) program, a classroom-based organization that works with kids grades 4-12 to increase the numbers of educationally disadvantaged students who graduate from high school prepared to enter higher education and pursue STEM careers. Students work with project scientists on field- and classroom-based experiences that employ inquiry-based learning to reveal ecological principles and explore local ecosystems.Despite substantial research exploring plant defense induction during and after herbivore attack, little is known about whether and how plants use pre-attack cues such as kairomones (herbivore-emitted chemicals not associated with attack that are detected by - and thus provide benefits to - a plant) to preemptively induce defense. Herbivore kairomones have recently been documented in multiple systems; slug/snail mucus, an easily obtained and manipulable kairomone, can be used to ask novel questions about plant risk perception and induced responses. The fact that slugs preferentially attack seedlings, a highly vulnerable life history stage, highlights the selective advantage of pre-attack mucus detection and response. The following questions are addressed in a long-lived woody plant system: How do different risk cues affect growth and defense of different-aged seedlings?; How do ontogenetic shifts in susceptibility determine patterns of responses?; What are the immediate and legacy consequences of risk perception and ontogeny in the field? These questions are asked using the slug Arion subfuscus and the sugar maple Acer saccharum in experiments exploring interactions between risk cue quality and seedling age over both short (~1 month) and long (1 yr.) time periods. This is the first study of how kairomones affect woody plant defense, growth, and subsequent herbivore vulnerability. The manipulation of herbivore cues, ontogeny, and differential susceptibility within and across seasons explores whether current plant defense reflects the ‘ghost of herbivory risk past’; present-day defense may often only make sense considering past information received by plants.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.