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

许多植物物种对拥挤和植被遮荫表现出特有的形态和生理反应。这种“避荫”反应是由透过或反射自绿色植被的红光与远红光波长之比（R：FR）的降低引起的。这种R：FR信号被称为光敏色素的感光分子所感知。 之前的研究表明，从这个项目中，光敏色素介导的茎伸长增加寿命繁殖的本地一年生凤仙花capensis（珠宝草或触摸我不）在密集的看台上，但植物诱导显示避荫反应在低密度遭受减少健身相对于非细长的植物。本研究将探讨遗传变异的近交系之间的避荫性状的表达在一个范围内的密度，并评估光敏色素介导的发展途径，这种变化的贡献。此外，避荫性状的自然选择将在一系列密度的领域进行测量，以预测避荫反应将如何在可变密度环境中演变。 该项目的结果将提供有关自然植物种群中光敏色素介导的避荫反应的遗传和进化的重要信息，并将为当前植物对光反应的分子，遗传，发育和生理机制的研究提供生态和进化背景。 它还将有助于为作物改良的选择策略提供信息，并为最近提出的通过基因工程作物提高产量的建议提供生态背景，其中避荫反应被阻断。

Many plant species exhibit characteristic morphological and physiological responses to crowding and vegetation shade. This "shade avoidance" response is cued by a reduction in the ratio of red to far-red wavelengths (R:FR) in light transmitted through or reflected from green vegetation. This R:FR signal is perceived by light-sensing molecules known as phytochromes. Prior research from this project has demonstrated that phytochrome-mediated stem elongation increases lifetime reproduction of the native annual Impatiens capensis (jewelweed or touch-me-not) in dense stands, but plants induced to display the shade avoidance response at low density suffer reduced fitness relative to non-elongated plants. The present study will examine genetic variation among inbred lines in expression of shade avoidance traits across a range of densities, and assess the contribution of phytochrome-mediated developmental pathways to this variation. In addition, natural selection on shade avoidance traits will be measured in the field across a range of densities, in order to predict how shade avoidance responses will evolve in variable density environments. The results of this project will provide important information about the genetics and evolution of phytochrome-mediated shade avoidance responses in natural plant populations, and will provide an ecological and evolutionary context for current research on the molecular, genetic, developmental, and physiological mechanisms underlying plant responses to light. It will also help to inform selection strategies for crop improvement and provide an ecological context for recent proposals to increase yield by genetically engineering crops in which shade avoidance responses are blocked.