Cryptochromes (CRYs) are blue-light receptors that regulate diverse aspects of plant growth. However, whether and how non-photoexcited CRYs function in darkness or non-blue-light conditions is unknown. Here, we show that CRY2 affects the Arabidopsis transcriptome even in darkness, revealing a non-canonical function. CRY2 suppresses cell division in the root apical meristem to downregulate root elongation in darkness. Blue-light oligomerizes CRY2 to de-repress root elongation. CRY2 physically interacts with FORKED-LIKE 1 (FL1) and FL3, and these interactions are inhibited by blue light, with only monomeric but not dimeric CRY2 able to interact. FL1 and FL3 associate with the chromatin of cell division genes to facilitate their transcription. This pro-growth activity is inhibited by CRY2’s physical interaction with FLs in darkness. Plants have evolved to perceive both blue-light and dark cues to coordinate activation and repression of competing developmental processes in above- and below-ground organs through economical and dichotomous use of ancient light receptors.

中文翻译：

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拟南芥蓝光感光器 CRY2 在黑暗中活跃以抑制根生长


隐花色素 （CRY） 是调节植物生长不同方面的蓝光受体。然而，非光激发 CRY 是否以及如何在黑暗或非蓝光条件下发挥作用尚不清楚。在这里，我们表明 CRY2 即使在黑暗中也能影响拟南芥转录组，揭示了非经典功能。CRY2 抑制根尖分生组织中的细胞分裂，在黑暗中下调根伸长。蓝光寡聚化 CRY2 以解除对根伸长的抑制。CRY2 与 FORKED-LIKE 1 （FL1） 和 FL3 发生物理相互作用，这些相互作用受到蓝光的抑制，只有单体而非二聚体 CRY2 能够相互作用。FL1 和 FL3 与细胞分裂基因的染色质结合以促进其转录。这种促生长活性被 CRY2 在黑暗中与 FLs 的物理相互作用所抑制。植物已经进化到可以感知蓝光和暗线索，通过经济和二分法使用古老的光感受器来协调地上和地下器官中竞争性发育过程的激活和抑制。