Collaborative Research: How to live on a (carbon and water) budget: Tree investment in chemical defenses across a gradient of physiological drought stress

合作研究：如何依靠（碳和水）预算生活：跨越生理干旱胁迫梯度的化学防御树木投资

• 批准号: 2139080
• 负责人: Henry Adams
• 金额: $ 23.2万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2023-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2139080&HistoricalAwards=false
• 关键词: Collaborative; Research; How; live; carbon

Drought-induced forest die-off is a global phenomenon with far-reaching ecological and economic impacts. In the western US, tree death from drought, high temperatures, and bark beetle outbreaks now exceeds forest growth. Despite increases in the frequency and severity of drought-related insect outbreaks, factors influencing a tree's susceptibility to insect herbivores, such as the presence of chemical defenses, have received little attention. In particular, it is unclear how drought causes trees to shift resources toward or away from the chemical defenses that deter insect attacks and the subsequent trade-offs that exist with other important plant functions. To address this critical knowledge gap, this study focuses on how pinon pine trees allocate their carbon resources toward defense and other physiological processes under increasing drought stress to avoid death by drought or bark beetle attack. This study uses an isotope labeling approach in both greenhouse and field experiments to track drought-induced changes in carbon allocation to specific chemical compounds that affect bark beetle choice and success. The project increases participation of Native American students through undergraduate recruitment for summer research assistantships as well as other underrepresented minorities in science through the development of two critical thinking modules and support for their adoption in rural middle school classrooms across Montana. The rate of tree mortality has increased across the globe yet the understanding of the mechanisms underlying tree death remains surprisingly limited. Most work to date on drought-related tree death has focused on understanding the coupled roles of carbon starvation and hydraulic failure, but drought is oftentimes accompanied by insect outbreaks that cause or contribute to tree mortality. Research has yet to determine when trees cease investment in effective chemical defenses against biotic attack along the continuum of drought stress, and how these shifts in carbon availability simultaneously impact other plant physiological processes. This study seeks a mechanistic understanding of how drought stress affects the interactions among tree hydraulic function, carbohydrate availability, and chemical defense. Using both greenhouse experiments and field drought manipulations this research will couple enzyme assays with the use of stable isotopes to identify mechanisms responsible for shifts in pinon pine allocation of recently fixed carbon at the level of individual compounds with known impacts on bark beetle behavior. These methods will also allow identification of trade-offs involved in the synthesis of defense compounds at different drought severities while also advancing fundamental understanding of tree physiology and whole tree C budgets. By providing a comprehensive understanding of the effects of drought-induced physiological stress on mechanisms determining defense against bark beetles, a new, more complete framework for assessing mechanisms of tree mortality will be developed. This research was co-funded by the Integrated Ecological Physiology Program in IOS/BIO and by the Established Program to Stimulate Competitive Research (EPSCoR).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.

干旱引起的森林死亡是一种全球现象，具有深远的生态和经济影响。在美国西部，因干旱、高温和树皮甲虫爆发而造成的树木死亡现已超过了森林的增长。尽管与干旱相关的昆虫爆发的频率和严重程度有所增加，但影响树木对食草昆虫的敏感性的因素（例如化学防御的存在）却很少受到关注。特别是，目前还不清楚干旱如何导致树木将资源转向或远离化学防御，以阻止昆虫的攻击以及随后与其他重要植物功能存在的权衡。为了解决这一关键的知识差距，本研究重点关注松树如何在干旱胁迫加剧的情况下将其碳资源分配给防御和其他生理过程，以避免因干旱或树皮甲虫攻击而死亡。这项研究在温室和田间实验中使用同位素标记方法来跟踪干旱引起的碳分配到影响树皮甲虫选择和成功的特定化合物的变化。该项目通过招募夏季研究助理的本科生来提高美国原住民学生的参与度，并通过开发两个批判性思维模块并支持蒙大拿州农村中学课堂采用这些模块来提高其他科学领域代表性不足的少数群体的参与度。全球范围内的树木死亡率有所上升，但对树木死亡机制的了解仍然非常有限。迄今为止，大多数关于与干旱相关的树木死亡的工作都集中在了解碳匮乏和水力衰竭的耦合作用上，但干旱常常伴随着导致或导致树木死亡的昆虫爆发。研究尚未确定，在干旱胁迫的连续过程中，树木何时​​停止投资有效的化学防御以抵御生物攻击，以及碳可用性的这些变化如何同时影响其他植物生理过程。本研究旨在从机制上理解干旱胁迫如何影响树木水力功能、碳水化合物可用性和化学防御之间的相互作用。这项研究将利用温室实验和田间干旱操作，将酶测定与稳定同位素的使用结合起来，以确定在已知对树皮甲虫行为有影响的单个化合物水平上，松树最近固定碳分配变化的机制。这些方法还将允许确定不同干旱严重程度下防御化合物合成所涉及的权衡，同时还增进对树木生理学和整棵树碳预算的基本了解。通过全面了解干旱引起的生理胁迫对确定树皮甲虫防御机制的影响，将开发一个新的、更完整的框架来评估树木死亡机制。 这项研究由 IOS/BIO 综合生态生理学计划和刺激竞争性研究既定计划 (EPSCoR) 共同资助。该奖项反映了 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。

项目成果

Drought impairs herbivore-induced volatile terpene emissions by ponderosa pine but not through constraints on newly assimilated carbon

干旱会损害草食动物引起的黄松挥发性萜烯排放，但不是通过限制新同化的碳来实现的

• DOI: 10.1093/treephys/tpad016
• 发表时间: 2023
• 期刊: Tree Physiology
• 影响因子: 4
• 作者: Malone, Shealyn C.;Simonpietri, Austin;Knighton, Walter B.;Trowbridge, Amy M.;Schnitzler, ed., Jörg-Peter
• 通讯作者: Schnitzler, ed., Jörg-Peter

Mechanisms of woody-plant mortality under rising drought, CO2 and vapour pressure deficit

• DOI: 10.1038/s43017-022-00272-1
• 发表时间: 2022-03-29
• 期刊: NATURE REVIEWS EARTH & ENVIRONMENT
• 影响因子: 42.1
• 作者: McDowell, Nate G.;Sapes, Gerard;Xu, Chonggang
• 通讯作者: Xu, Chonggang

Tree defence and bark beetles in a drying world: carbon partitioning, functioning and modelling

• DOI: 10.1111/nph.16173
• 发表时间: 2019-10-08
• 期刊: NEW PHYTOLOGIST
• 影响因子: 9.4
• 作者: Huang, Jianbei;Kautz, Markus;Hartmann, Henrik
• 通讯作者: Hartmann, Henrik