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.

9708114 Schmitt 许多植物物种对拥挤和植被遮荫表现出特征性的形态反应，例如茎伸长和分枝减少。 这种“避荫反应”是由绿色植被透射或反射的光中红色与远红色波长之比（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使植物能够预测并避免对茂密林分中的光线竞争，从而对植物有益。该项目的最新结果有力地支持了这一假设。 在一项田间实验中，茎伸长增加了常见一年生凤仙花在密集林中的繁殖，但在低密度下诱导表现出避荫反应的植物相对于未伸长的植物而言，其适应性降低，这显然是由于无法测量的生理成本。拟议研究的目标是检查避荫反应的遗传基础和在田间选择反应的潜在机制，并测试反应的生理、生态和遗传成本。 对 R:FR 的形态反应程度不同的复制自交系将以操纵的密度和群体组成种植到自然群体中，以研究选择对避荫性状的作用水平。 伸长和非伸长的幼苗将在不同水平的水和营养物下生长，以确定避荫性状可能代价高昂的条件。 这项研究将整合遗传、生理和群体生物学方法来研究光敏色素介导的植物避荫反应。 它将为这些反应在自然群体中的作用提供重要的见解。 研究结果还将为植物分子生物学家和发育生物学家当前关于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中，这项研究还将深入了解提高农业产量的可能选择策略。