Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Genes Dev. 2012 Apr 15;26(8):785-90. doi: 10.1101/gad.187849.112.
Plants sense neighbor proximity as a decrease in the ratio of red to far-red light, which triggers a series of developmental responses. In Arabidopsis, phytochrome B (PHYB) is the major sensor of shade, but PHYB excitation has not been linked directly to a growth response. We show that the basic helix-loop-helix (bHLH) transcription factor PIF7 (phytochrome-interacting factor 7), an interactor of PHYB, accumulates in its dephosphorylated form in shade, allowing it to bind auxin biosynthetic genes and increase their expression. New auxin synthesized through a PIF7-regulated pathway is required for shade-induced growth, linking directly the perception of a light quality signal to a rapid growth response.
植物通过感知红光与远红光的比值来判断临近植物的距离，这种感知会触发一系列发育反应。在拟南芥中，光敏色素 B（PHYB）是主要的遮光传感器，但 PHYB 的激活并未与生长反应直接相关。我们发现，基本螺旋-环-螺旋（bHLH）转录因子 PIF7（光敏色素相互作用因子 7），作为 PHYB 的相互作用因子，在遮荫条件下以去磷酸化的形式积累，从而使其能够与生长素生物合成基因结合并增加其表达。通过 PIF7 调控的途径合成的新生长素对于遮荫诱导的生长是必需的，它直接将光质信号的感知与快速生长反应联系起来。
