Evolution of phytochrome signalling and nuclear transport

在种子植物中，光敏色素A（phyA）光受体在远红光富集环境中的生存中起着关键作用，并且对于非常低强度的光的响应是必不可少的。在光激活后，phyA与FHY 1结合，FHY 1介导phyA核运输和积累。相比之下，隐花植物蛋白被认为是胞质和/或膜相关蛋白。虽然phy基因谱系分裂成phyA和其他phys仅发生在种子植物中，但FHY 1样蛋白可以在不含phyA样phys的蕨类植物、苔藓和绿色藻类中鉴定。所有这些隐花植物FHY 1蛋白都与phyA以及隐花植物phys相互作用。有趣的是，phyA信号传导的其他关键组分也存在于立碗藓属基因组中，这表明phyA可能已经采用了前隐花植物的信号系统和隐花植物的生理功能在细胞核中也有作用。将采用表达YFP标记的phys的转基因立碗藓属品系来检验该假设。此外，phyA/隐花植物phys的FHY 1结合位点将使用随机诱变/Y2 H方法进行映射，这将进一步深入了解phyA信号转导和phy/FHY 1系统如何进化。

In seed plants the phytochrome A (phyA) photoreceptor plays a key role in survival in far-red light enriched environments and it is essential for responses to very low intensities of light. After activation by light phyA binds to FHY1, which mediates phyA nuclear transport and accumulation. In contrast, cryptogam phys are believed to be cytosolic and/or membrane associated proteins. Although the split of the phy gene lineage into phyA and other phys occurred only in seed plants FHY1 like proteins can be identified in ferns, mosses and green algae, which do not contain phyA like phys. All these cryptogam FHY1 proteins interact with phyA as well as with cryptogam phys. Interestingly, also other key components of phyA signalling are represented in the Physcomitrella genome suggesting that phyA may have adopted a pre-existing signalling system from cryptogams and that also cryptogam phys have a function in the nucleus. Transgenic Physcomitrella lines expressing YFP tagged phys will be employed to test this hypothesis. Moreover, the FHY1 binding site of phyA/cryptogam phys will be mapped using a random mutagenesis/Y2H approach, which will provide further insight into how phyA signalling and the phy/FHY1 system evolved.