光是调节植物生长发育的重要环境因子。面对遮荫信号，避荫植物会诱导以茎和叶柄的伸长为主的一系列形态和生理变化，统称为避荫反应；耐荫植物则不会诱导伸长生长，而是产生一系列可能帮助植物应对遮荫胁迫的生理和形态变化。由于缺乏合适的研究体系，我们对耐荫反应如何帮助植物应对遮荫，其分子机制等都缺乏了解。拟南芥虽然是典型的避荫植物，但是研究表明在拟南芥中存在负调控避荫反应的机制，我们称之为拟南芥的耐荫反应。在本申请中，我们通过设定不同的遮荫条件，诱导拟南芥产生以避荫反应或耐荫反应为主的表型。通过比较这两种遮荫条件下植物的生理、形态、抗逆、对激素的应答等方面的变化，结合转录组分析和遗传筛选和分析，我们希望获得耐荫调控中关键组分，解析其作用机制，构建耐荫反应的调控网络。该研究结果不仅能帮助我们利用避荫作物自身的耐荫反应抑制不利于农业生产的避荫反应，还为研究耐荫植物的耐荫反应提供线索。

Light is an important environmental signal that directs plant development throughout its whole life span. In response to vegetative shade, shade avoiding plants will induce a series of responses including stem and petiole elongation that are collectively called the shade avoidance responses. Shade tolerant plants, on the other hand, do not induce elongation growth, but will also generate morphological and physiological changes that may allow plants to survive under shade. Due to the lack of a proper research system, little is known about how the shade tolerance responses help plants to endure shade and what is the underlying molecular mechanism. Arabidopsis thaliana is a typical shade avoiding plant. It was previously reported that the shade avoidance responses can be negatively regulated in Arabidopsis as well, which we termed the shade tolerance response in Arabidopsis. In this study, we set up two shade conditions to induce shade avoidance and shade tolerance responses in Arabidopsis. We will then investigate the morphological and physiological changes in plants under these two conditions, their changes in sensitivity to hormones and various stresses. Through approaches such as transcriptional profiling, genetic screen and analysis, we aim to identify key signaling components in the shade tolerance response, uncover their functions and construct the signaling network. Results from this study will not only allow us to utilize the shade tolerance response of the shade avoiding crops to attenuate traits that are detrimental to crop yield, but also will set a starting point for understanding the molecular mechanism of the shade tolerance responses in the shade tolerance plant species.