Light limitation represents a significant threat to plant survival. Shade-intolerant species have, therefore, evolved mechanisms to detect and avoid shading by neighbors. Plants detect the proximity and density of neighboring vegetation by monitoring alterations in light quality (1). Phytochrome photoreceptors detect changes in the ratio of red (R) to far-red light (FR), with phytochrome B performing a dominant role. R is absorbed by living vegetation and used for photosynthesis, whereas the majority of FR is transmitted through and reflected within canopies. R:FR is, therefore, reduced proportionally with increasing depth of canopy (1). Early perception of encroaching shade enables plants to rapidly elongate stems and elevate leaves to overtop competitors and avoid light limitation. Such responses are termed shade avoidance and can promote survival in mixed stands (1). Shade avoidance is regulated by a group of transcription factors named PHYTOCHROME INTERACTING FACTORS (PIFs), with PIF4, PIF5, and PIF7 performing dominant roles (2⇓–4). These PIFs collectively promote synthesis of the growth-promoting hormone auxin (4, 5). In sunlight (high R:FR), phytochrome B becomes …

中文翻译：

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昼夜节律的PRR蛋白在避光时调用时间。

光照限制对植物生存构成重大威胁。因此，对树荫不敏感的物种已经进化出机制，可以检测并避免邻居的树荫。植物通过监测光质量的变化来检测邻近植物的接近度和密度（1）。植物色素感光剂检测红色（R）与远红色光（FR）的比率变化，其中植物色素B占主导地位。R被活植物吸收并用于光合作用，而大部分FR通过树冠传播并在树冠内反射。因此，R：FR随树冠深度的增加而按比例降低（1）。对阴凉处的早期感知使植物能够快速拉长茎并将叶提升到高位竞争者，并避免光照限制。这种反应被称为避光，可以促进混合林中的生存（1）。避荫是由一组命名的光敏色素相互作用的因素（PIFS）转录因子的调控，以PIF4，PIF5和PIF7执行主导的角色（2 ⇓ - 4）。这些的PIF共同促进生长促进激素生长素（合成4，5）。在阳光下（高R：FR），植物色素B变为…