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施密特许多植物物种对拥挤和植被遮荫表现出独特的形态反应，如茎伸长和分枝减少。绿色植物透过或反射的光中，红光波长与远红波长(R：FR)的比率降低，这就是“遮荫反应”；这种R：FR信号被称为光敏色素的感光分子所感知。据推测，光敏色素介导的遮荫回避反应使植物能够预见和避免密集林分中对光的竞争，从而对植物有利。该项目的最新结果有力地支持了这一假设。在田间试验中，茎的伸长增加了密林中常见的一年生凤仙花的繁殖量，但在低密度下诱导表现出遮荫回避反应的植株比不伸长的植株的适合度降低，这显然是由于未测量的生理成本。这项研究的目的是研究遮荫回避反应的遗传基础和田间选择反应的潜在机制，并测试这种反应的生理、生态和遗传成本。对R：FR的形态反应大小不同的复制自交系将以操纵密度和群体组成种植到自然群体中，以研究选择对遮荫回避性状的作用水平。将在不同的水分和营养水平下生长伸长和不伸长的幼苗，以确定在什么条件下遮荫特征可能是昂贵的。这项研究将结合遗传学、生理学和种群生物学方法来研究植物中光敏色素介导的遮荫回避反应。它将为这些反应在自然人口中的作用提供重要的见解。这些结果还将为植物分子生物学家和发育生物学家目前关于植物对光反应的潜在遗传基础的研究提供一个生态和进化背景。由于大多数作物都生长在密林中，这项研究也将为提高农业产量提供可能的选择策略。