Collaborative Research: Consequences of Leaf Lifetime for Photosynthetic Physiology, Secondary Metabolism, and Anatomyin Tropical Plants

最近的许多工作集中在非生物环境的动态性质，以及植物对这些变化条件的反应方式上。特别强调的是，植物生长和防御两个基本方面的光可用性变化的重要性。然而，我们对光对光合作用和防御性次生代谢物合成的影响的了解主要来自温带强光环境和农业系统。在潮湿的热带森林中，森林地面的光线利用率极低（1%的充分阳光），高光照持续时间从几秒到几小时不等，这取决于上面树冠开口的大小。因此，树苗和林下植物必须能够在极低的光照水平下生存，同时能够利用短时间的强光和可能有害的光。尽管世界上大多数物种都在这种条件下生存，但人们对这些耐阴物种如何适应光照的长期和短期变化知之甚少。研究人员将收集一系列耐阴热带木本植物的光合生理学、次生代谢物和叶片解剖学的比较数据。这将使他们能够评估长期和短期光可用性变化的生理机制，并跟踪资源是如何分配给生长和防御的差异。

Much recent work has focused on the dynamic nature of the abiotic environment, and on the ways plants respond to these changing conditions. In particular, emphasis has been placed on the importance of variation in light availability for two fundamental aspects of plant performance: growth and defense. However, our understanding of light effects on photosynthesis and synthesis of defensive secondary metabolites comes primarily from temperate high light environments and agricultural systems. In humid tropical forests, light availability at the forest floor is extremely low (1% full sunlight), with periods of higher light lasting from seconds to hours, depending on the size of the opening in the canopy above. Tree saplings and understory plants must therefore be capable of persisting at extremely low light levels, yet be able to take advantage of short periods of intense and perhaps damaging light. Little is known about how these shade-tolerant species adjust to long-and short-term variation in light availability, despite the fact the majority of the world's species exists under these conditions. The investigators will collect comparative data on photosynthetic physiology, secondary metabolites, and leaf anatomy for a range of shade-tolerant tropical woody species. This will enable them to assess the physiological mechanisms underlying adjustments to long-and short-term variation in light availability, and to track how resources are differentially allocated to growth vs defense.