RUI: Contractile Roots: Their Role in Anchorage and Resource Acquisition in the Agavaceae

本研究的目的是探讨根收缩（纵向缩短）如何帮助植物根系执行两个主要功能：锚定和资源获取。收缩根以前曾被研究为一种将植物拉到更有利的土壤深度或帮助在离其亲本植物一定距离处建立分支的手段。虽然收缩的过程已被调查的一些物种，相关的解剖修改根吸水的影响还没有被检查。收缩根，这是以前描述的龙舌兰属的一个成员，似乎是广泛的龙舌兰科，其中包括几个物种的生态重要性在美国西南部和墨西哥。本研究的指导假设是，收缩根不仅提高幼苗建立和克隆繁殖季节性干旱的栖息地，但也提高了水分吸收的地区降雨量少，有限。该假设将通过比较龙舌兰科中不同生境的成对物种的收缩根的结构和功能来检验（例如，草原与沙漠），生长习性（例如，多肉植物对非多肉植物，莲座丛对树状），以及繁殖方法（例如，经常是植物人vs.严格的性关系）。根收缩和芽位移的量将在实验室和普通花园中的各种条件下进行量化，并且将部分挖掘加州南部的龙舌兰和丝兰的本地物种的根系，以确定该领域的根收缩的程度。将沿着解剖学特征，如微管方向，细胞形状和大小，细胞活力和细胞壁的修改，特别是当它们影响水的吸收和运输的收缩与非收缩的根的水吸收进行研究。该研究将包括几个尺度（细胞器到植物家族），并采用来自几个领域（解剖学，生态学和生理学）的技术，为本科生学习和未来研究的准备提供多个但综合的选择。由于西方学院作为一个致力于多样性的机构的声誉和它在洛杉矶东北部的位置，机会不足的学生成为参与研究是伟大的。此外，这项研究有望阐明收缩根在生态和经济上重要的植物群的功能意义，并首次研究收缩对根获取和运输水的能力的影响。

The purpose of this study is to investigate how root contraction (longitudinal shortening) can help plant root systems perform two primary functions: anchorage and resource acquisition. Contractile roots have been studied previously as a means of pulling a plant to a more favorable soil depth or helping establish an offshoot at some distance from its parent plant. Although the process of contraction has been investigated for a number of species, the effects of the associated anatomical modifications on root water uptake have not been examined. Contractile roots, which have been described previously for one member of the genus Agave, appear to be widespread in the family Agavaceae, which includes several species of ecological importance in the southwestern U.S. and Mexico. The guiding hypothesis of this study is that contractile roots not only improve seedling establishment and clonal propagation in seasonally dry habitats but also enhance water uptake in regions of infrequent and limited rainfall. The hypothesis will be tested by comparing the structure and function of contractile roots for paired species in the Agavaceae that differ in habitat (e.g., grassland vs. desert), growth habit (e.g., succulent vs. non-succulent, rosette vs. tree-like), and method of reproduction (e.g., frequently vegetative vs. strictly sexual). The amount of root contraction and shoot displacement will be quantified under various conditions in the laboratory and in a common garden, and root systems of native species of agave and yucca in southern California will be partially excavated to determine the extent of root contraction in the field. Water uptake by contractile versus non-contractile roots will be investigated along with anatomical features such as microtubule orientation, cell shape and size, cell vitality, and cell wall modifications, particularly as they affect water absorption and transport. The study will encompass several scales (organelle to plant family) and employ techniques from several fields (anatomy, ecology, and physiology), providing multiple yet integrated options for undergraduate learning and preparation for future research. Due to the reputation of Occidental College as an institution committed to diversity and its location in northeast Los Angeles, the opportunity for under-represented students to become involved in the research is great. In addition, the study promises to illuminate the functional significance of contractile roots in an ecologically and economically important group of plants and to examine for the first time the effects of contraction on the ability of roots to acquire and transport water.