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，它们也远不是毫无防备地对抗它们的食草动物。虽然探索植物如何保护自己的研究主要集中在植物防御系统在应对食草动物攻击时发生的变化上，但最近的研究表明，植物甚至在攻击开始之前就可以检测到食草动物的暗示(称为凯洛蒙)并做出反应。蜗牛和鼻涕是攻击种子和幼苗的食草动物，它们的粘液会在幼苗中触发防御反应，帮助植物在随后受到鼻涕虫或其他食草动物的攻击时幸存下来。这种防御措施可能对实生糖枫树尤为重要，这是美国东北部的一种标志性树木，对枫糖行业至关重要，整个行业都在衰落。一种入侵的鼻涕虫，暗色的Arion，对新萌发的糖枫幼苗构成了主要威胁；这个项目研究了这种鼻涕虫的粘液如何影响从幼苗到树苗的各种年龄的糖枫的抗食草动物防御。它还评估了早期接触粘液是否有助于保护糖枫免受从吉普赛飞蛾到白尾鹿等后来到达的食草动物的伤害。该项目还资助了总部位于罗德岛的科学与数学研究性学习计划(SMILE)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，增加高中毕业后准备进入高等教育并从事STEM职业的教育弱势学生的数量。学生与项目科学家一起进行基于实地和课堂的体验，利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。尽管有大量研究探索草食动物攻击期间和之后的植物防御诱导，但关于植物是否以及如何使用攻击前的线索，如凯洛蒙(与攻击无关的草食动物释放的化学物质，被植物检测到并因此提供好处)来先发制人地诱导防御，人们知之甚少。最近在多种系统中发现了食草性凯龙酮；鼻涕/蜗牛粘液是一种容易获得和可操作的凯龙酮，可以用来提出关于植物风险感知和诱导反应的新问题。鼻涕虫优先攻击幼苗这一高度脆弱的生活史阶段的事实，突出了攻击前粘液检测和反应的选择性优势。在一个长期存活的木本植物系统中解决了以下问题：不同的风险信号如何影响不同年龄的幼苗的生长和防御？易感性的个体发育变化如何决定反应模式？风险感知和个体发育在田间的直接和遗留后果是什么？这些问题是在短期(~1个月)和长期(1年)的风险线索质量和苗龄之间的交互作用的实验中，使用冬虫夏草和糖枫进行的。时间段。这是关于凯洛蒙如何影响木本植物的防御、生长和随后的食草动物脆弱性的第一项研究。在季节内和跨季节对食草动物线索、个体发育和差异敏感度的操纵探索了当前的植物防御是否反映了“过去草食风险的幽灵”；现在的防御通常只有考虑到植物过去收到的信息才有意义。这个奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.