The Structure-Function Relationships of Tracheid-Based Xylem: An Integrated Approach

现代陆地植物的生产力与植物维管系统的结构和功能密切相关。具体地说，是木质部组织决定了高等植物中水分运输的效率。 关于限制木本植物水分运输的结构-功能权衡，人们已经知道了很多，但很少有工作研究它们的亲戚蕨类植物的维管性能。与针叶树木材一样，蕨类植物木质部主要由单细胞中空导管组成，但其区别在于缺乏木材和其他促进针叶树运输效率的关键解剖特征。 这种原始类型的初生木质部所施加的水力和光合作用限制是什么？它如何帮助我们理解维管组织的进化？ 该项目的目标是研究蕨类植物木质部的结构和功能，使用液压，化学和解剖学方法，在整个蕨类植物进化树。 这些数据将为我们提供一个更深入的了解植物血管功能的演变，并将被用来模拟水运输的Archaeopteris，泥盆纪的针叶蕨类植物的混合代表第一个现代树。第二个长期的努力将监测当地蕨类植物物种的形态和生理在红杉林下沿着降雨梯度跨越北方到中部加州。 蕨类植物叶片的大小直接关系到水的可用性，并可以作为一个方便的指示林下植被响应降水量的变化。这一实地项目的目的是增加代表性不足的本科生对自然科学的参与，让学生了解气候变化，并建立一个关于加州沿海林下群落结构的长期数据库。

The productivity of modern land plants is coupled to the structure and function of the plant vascular system. Specifically, it is the xylem tissue that determines the efficiency of water transport in higher plants. A great deal is known about the structure-function trade-offs that limit water transport in woody taxa, and yet very little work has examined the vascular performance of their relatives, the ferns. Like conifer wood, fern xylem is primarily comprised of single-celled, hollow conduits, but it is distinguished by the absence of wood and other key anatomical features that promote transport efficiency in conifers. What are the hydraulic and photosynthetic limitations imposed by this primitive type of primary xylem, and how can it inform our understanding of the evolution of vascular tissue? The goal of this project is to examine the structure and function of fern xylem using hydraulic, chemical and anatomical methods, across the fern evolutionary tree. These data will provide us with a deeper understanding of the evolution of plant vascular function, and will be used to model water transport in Archaeopteris, a Devonian conifer-fern hybrid representing the first modern tree. A second, long-term effort will monitor the morphology and physiology of local fern species in the redwood forest understory along a precipitation gradient spanning northern to central California. Fern frond size is directly related to water availability, and can serve as a convenient indicator of understory vegetation response in response to changes in precipitation. This field-based project aims to increase the participation of under-represented undergraduates in the natural sciences, inform students about climate change and build a long-term database of understory community structure in coastal California.