Integration of Phytochrome and Cryptochrome Signals Determines Plant Growth during Competition for Light
Integration of Phytochrome and Cryptochrome Signals Determines Plant Growth during Competition for Light
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DOI：
10.1016/j.cub.2016.10.031
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发表时间：
2016-12-19
期刊：
影响因子：
9.2
通讯作者：
Pierik, Ronald
中科院分区：
文献类型：
--
作者：
de Wit, Mieke;Keuskamp, Diederik H.;Pierik, Ronald
茂密植被中的植物主要通过光质的变化来感知它们的邻居。最初，红色（R）和远红色（FR）光之间的比率由于在遮光发生之前FR被植物组织反射而降低。光敏色素光感受器对低R：FR的感知诱导了避荫反应[1]，其中加速的叶器官伸长生长是一个重要特征。低R：FR诱导的光敏色素失活导致转录因子光敏色素相互作用因子（PIFs）4、5和7的积累和激活，并随后表达其生长介导靶点[2，3]。当真正的阴影发生时，由于叶绿素的吸收，透射光在红色和蓝色（B）波长中特别耗尽[4]。虽然在自然界中不会单独发生蓝色波长的减少，但长期暴露于低B光会诱导依赖于隐花色素光感受器和转录因子PIF 4和PIF 5的避荫样反应[5-7]。我们表明，在拟南芥中，低B与低R：FR相结合，增强叶柄伸长类似于植被遮荫，植物竞争中的低B响应提供了功能背景。低B通过PIF 4、PIF 5和PIF 7增强低R：FR应答，并且其涉及增加的PIF 5丰度和转录变化。低B通过降低负调节因子的基因表达和降低HFR 1水平来减弱低R：FR诱导的负反馈环。对组合光敏色素和隐花色素失活的增强的响应显示了多个光线索如何被整合以微调植物对变化的环境的响应。
Plants in dense vegetation perceive their neighbors primarily through changes in light quality. Initially, the ratio between red (R) and far-red (FR) light decreases due to reflection of FR by plant tissue well before shading occurs. Perception of low R:FR by the phytochrome photoreceptors induces the shade avoidance response [1], of which accelerated elongation growth of leaf-bearing organs is an important feature. Low R: FR-induced phytochrome inactivation leads to the accumulation and activation of the transcription factors PHYTOCHROME-INTERACTING FACTORs (PIFs) 4, 5, and 7 and subsequent expression of their growth-mediating targets [2, 3]. When true shading occurs, transmitted light is especially depleted in red and blue (B) wavelengths, due to absorption by chlorophyll [4]. Although the reduction of blue wavelengths alone does not occur in nature, long-term exposure to low B light induces a shade avoidance-like response that is dependent on the cryptochrome photoreceptors and the transcription factors PIF4 and PIF5 [5-7]. We show in Arabidopsis thaliana that low B in combination with low R: FR enhances petiole elongation similar to vegetation shade, providing functional context for a low B response in plant competition. Low B potentiates the low R: FR response through PIF4, PIF5, and PIF7, and it involves increased PIF5 abundance and transcriptional changes. Low B attenuates a low R: FR-induced negative feedback loop through reduced gene expression of negative regulators and reduced HFR1 levels. The enhanced response to combined phytochrome and cryptochrome inactivation shows how multiple light cues can be integrated to fine-tune the plant's response to a changing environment.