Studies on a blue-light sensing system of fern Adiantum PHY3 photoreceptor

绝热体光感受器PHY3既是光敏色素又是促光素。PHY3包含光敏色素的“光感核心模块”（Photosensory Core Module， PCM）， PHY3 PCM不仅能感知红光信号，还能感知蓝光信号。为了研究PHY3 PCM的蓝光传感分子机制，本研究将PHY3 PCM替换为拟南芥光敏色素PCM。这些嵌合光感受器可以诱导蓝光依赖的下胚轴向光响应，但没有观察到明显的红光诱导下胚轴向光源弯曲。因此，PHY3 PCM不能与拟南芥phyA或phyB的相应区域互换。将PHY3 PCM氨基酸序列与其他光敏色素PCM进行比较，发现在PCM区域存在PHY3特异性空白。这些结果表明，PCM中的这种PHY3特征间隙可能赋予PHY3 PCM区域蓝光感知能力。

Adiantum photoreceptor PHY3 acts as both a phytochrome and a phototropin. PHY3 includes "Photosensory Core Module" (PCM) of phytochromes and PHY3 PCM could perceive not only red- but also blue-light signals. To study blue-light sensing molecular mechanisms of PHY3 PCM, I substituted PHY3 PCM to Arabidopsis phytochrome PCMs. These chimeric photoreceptors can induce blue-light dependent hypocotyl phototropic response, however, no significant red-light induced hypocotyl bending toward the light source was observed. Hence, PHY3 PCM could not be interchangeable to a corresponding region of either phyA or phyB of Arabidopsis. I compared PHY3 PCM amino acid sequence to other phytochrome PCMs and found the PHY3 specific gaps in PCM region. These results suggest that such a PHY3 characteristic gaps in PCM could confer blue-light sensing ability to PHY3 PCM region.