Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona 08193, Spain.
Institute for Plant Molecular and Cell Biology (IBMCP), CSIC-UPV, València 46022, Spain.
Plant Physiol. 2024 Nov 4;196(3):2048-2063. doi: 10.1093/plphys/kiae417.
After the perception of vegetation proximity by phytochrome photoreceptors, shade-avoider plants initiate a set of responses known as the shade avoidance syndrome (SAS). Shade perception by the phytochrome B (phyB) photoreceptor unleashes the PHYTOCHROME INTERACTING FACTORs and initiates SAS responses. In Arabidopsis (Arabidopsis thaliana) seedlings, shade perception involves rapid and massive changes in gene expression, increases auxin production, and promotes hypocotyl elongation. Other components, such as phyA and ELONGATED HYPOCOTYL 5, also participate in the shade regulation of the hypocotyl elongation response by repressing it. However, why and how so many regulators with either positive or negative activities modulate the same response remains unclear. Our physiological, genetic, cellular, and transcriptomic analyses showed that (i) these components are organized into 2 main branches or modules and (ii) the connection between them is dynamic and changes with the time of shade exposure. We propose a model for the regulation of shade-induced hypocotyl elongation in which the temporal and spatial functional importance of the various SAS regulators analyzed here helps to explain the coexistence of differentiated regulatory branches with overlapping activities.
植物感光体感知到植物接近后，遮阴回避植物会启动一系列被称为遮阴回避综合征（SAS）的反应。植物感光体 B（phyB）接收遮阴信号，引发 PHYTOCHROME INTERACTING FACTORs（PIFs），启动 SAS 反应。在拟南芥（Arabidopsis thaliana）幼苗中，遮阴感知涉及基因表达的快速和大量变化，增加生长素的产生，并促进下胚轴伸长。其他成分，如 phyA 和 ELONGATED HYPOCOTYL 5（ELH5），也通过抑制其作用参与下胚轴伸长反应的遮阴调节。然而，为什么和如何有如此多的具有正向或负向活性的调节剂来调节相同的反应仍然不清楚。我们的生理、遗传、细胞和转录组学分析表明，（i）这些成分组织成 2 个主要分支或模块，（ii）它们之间的连接是动态的，并随着遮阴暴露时间的变化而变化。我们提出了一个调节遮阴诱导下胚轴伸长的模型，其中这里分析的各种 SAS 调节剂的时间和空间功能重要性有助于解释具有重叠活性的分化调节分支的共存。
