Key Laboratory of Photobiology; Institute of Botany; The Chinese Academy of Sciences; Beijing, PR China.
Plant Signal Behav. 2013 Aug;8(8). doi: 10.4161/psb.25026. Epub 2013 Jun 4.
Light plays a vital role in seedling de-etiolation during which it remarkably inhibits hypocotyl growth and promotes cotyledon opening and the synthesis of chlorophyll and anthocyanin. After light perception, photoreceptors act to repress two main branches of the light signaling, PIFs and COP1-HY5. We recently identified PKL/EPP1, a chromatin remodeling factor, as a new component in regulating light-mediated hypocotyl growth. In this study, we found that EPP1 acts additively with SPA1 to repress seedling de-etiolation. Moreover, the expression of EPP1 is downregulated specifically in the hypocotyl region of the cop1 mutant compared with that of the wild type. We further found that EPP1 drastically inhibits both the protein and transcript levels of HY5, but not vice versa, indicating that HY5 acts downstream of EPP1. We thus propose a model in which EPP1 defines a new repressor and mediates a distinct signaling pathway of photomorphogenesis.
光在幼苗脱黄化过程中起着至关重要的作用，它显著抑制下胚轴生长，促进子叶张开以及叶绿素和花青素的合成。在光感知后，光受体作用于抑制光信号的两个主要分支，PIFs 和 COP1-HY5。我们最近鉴定出 PKL/EPP1，一种染色质重塑因子，是调节光介导的下胚轴生长的新成分。在这项研究中，我们发现 EPP1 与 SPA1 协同作用抑制幼苗脱黄化。此外，与野生型相比，cop1 突变体中 EPP1 的表达特异性地下调在下胚轴区域。我们进一步发现 EPP1 强烈抑制 HY5 的蛋白和转录本水平，但反之则不然，表明 HY5 位于 EPP1 的下游。因此，我们提出一个模型，其中 EPP1 定义了一个新的抑制剂，并介导光形态建成的一个独特的信号通路。
