Response to Crowding and Vegetation Shade in Impatiens capensis: Genetic Variation and Fitness Consequences

凤仙花对拥挤和植被遮荫的反应：遗传变异和适应性后果

• 批准号: 9708114
• 负责人: Johanna Schmitt
• 金额: $ 9万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9708114&HistoricalAwards=false
• 关键词: Response; Crowding; Vegetation; Shade; Impatiens

9708114 Schmitt Many plant species exhibit characteristic morphological responses to crowding and vegetation shade, such as stem elongation and reduced branching. This "shade avoidance response" is cued by a reduction in the ratio of red to far-red wavelengths (R:FR) in light transmitted or reflected from green vegetation; this R:FR signal is perceived by light-sensing molecules called phytochromes. It has been hypothesized that phytochrome-mediated shade avoidance responses are beneficial to plants by enabling them to anticipate and avoid competition for light in dense stands. Recent results from this project strongly support this hypothesis. In a field experiment, stem elongation increased the reproduction of the common annual Impatiens capensis in dense stands, but plants induced to display the shade avoidance response at low density suffered reduced fitness relative to nonelongated plants, apparently due to an unmeasured physiological cost. The goals of the proposed research are to examine the genetic basis of the shade avoidance response and potential mechanisms for selection on the response in the field, and to test for physiological, ecological, and genetic costs of the response. Replicated inbred lines differing in the magnitude of morphological response to R:FR will be planted into a natural population at manipulated densities and group compositions to study the level at which selection acts on shade avoidance traits. Elongated and nonelongated seedlings will be grown under different levels of water and nutrients, to determine the conditions under which shade avoidance traits may be costly. This research will integrate genetic, physiological, and population biology approaches to the study of phytochrome-mediated shade avoidance responses in plants. It will provide important insights into the role of these responses in natural populations. The results will also provide an ecological and evolutionary context for current research by plant molecular biolog ists and developmental biologists on the underlying genetic basis for plant responses to light. Since most crops are grown in dense stands, this study will also provide insight into possible selection strategies for improvement of agricultural yields.

许多植物对拥挤和植被遮荫表现出特有的形态响应，如茎伸长和分枝减少。这种“避影反应”是由绿色植被透射或反射的光中红光与远红光波长之比（R:FR）的减少引起的；这种R:FR信号被称为光敏色素的光敏分子感知。据推测，光敏色素介导的避荫反应对植物是有益的，使它们能够预测和避免在茂密的林分中对光的竞争。该项目的最新结果有力地支持了这一假设。在田间试验中，茎长增加了密集林分中常见一年生凤仙花（Impatiens capensis）的繁殖，但在低密度下表现出遮荫回避反应的植株的适合度相对于非伸长的植株降低，这显然是由于未测量的生理成本。本研究的目的是研究避荫反应的遗传基础和田间选择避荫反应的潜在机制，并测试避荫反应的生理、生态和遗传成本。将对R:FR有不同形态响应程度的复制自交系，在控制密度和群体组成的条件下种植到一个自然群体中，研究选择在何种程度上对避荫性状起作用。细长和非细长的幼苗将在不同的水分和养分水平下生长，以确定在哪些条件下避荫性状可能是昂贵的。本研究将整合遗传学、生理学和种群生物学的方法来研究植物中光敏色素介导的避荫反应。它将为了解这些反应在自然种群中的作用提供重要见解。该研究结果还将为植物分子生物学家和发育生物学家目前对植物对光反应的潜在遗传基础的研究提供生态和进化背景。由于大多数作物生长在密集的林分中，这项研究也将为提高农业产量的可能选择策略提供见解。