An Evolutionarily Conserved Signaling Mechanism Mediates Far-Red Light Responses in Land Plants
An Evolutionarily Conserved Signaling Mechanism Mediates Far-Red Light Responses in Land Plants
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DOI：
10.1105/tpc.112.104331
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发表时间：
2013-01-01
期刊：
影响因子：
11.6
通讯作者：
Hiltbrunner, Andreas
中科院分区：
文献类型：
--
作者：
Possart, Anja;Hiltbrunner, Andreas
光敏色素是植物发育和适应环境的重要光感受器。光敏色素A （PHYA）对远红（FR）高辐照度响应（HIRs）至关重要，而远红高辐照度响应使植物能够在荫蔽条件下生长，具有特殊的生态学意义。PHYA和hir被认为是种子植物独有的，因为种子植物和隐生植物（如蕨类和苔藓）的分化早于PHYA的进化。种子植物光敏色素转运进入细胞核并调控基因表达。相比之下，很少有证据表明隐花植物光敏色素的核定位和功能。在这里，我们确定了隐芽植物对FR光的反应，这与种子植物中的PHYA信号非常相似。在苔藓类小立壶和蕨类植物中，光敏色素响应于光在细胞核中积累。尽管植物光敏色素的进化独立于PHYA，但我们发现植物光敏色素的一个分支具有PHYA的分子特性。我们认为，在现代种子植物和隐花植物的最后一个共同祖先中，类似HIR的反应已经进化出来，并且HIR信号比PHYA更古老。因此，种子植物中的其他光敏色素可能在进化过程中失去了介导hir的能力，而不是PHYA获得了这种能力。
Phytochromes are plant photoreceptors important for development and adaptation to the environment. Phytochrome A (PHYA) is essential for the far-red (FR) high-irradiance responses (HIRs), which are of particular ecological relevance as they enable plants to establish under shade conditions. PHYA and HIRs have been considered unique to seed plants because the divergence of seed plants and cryptogams (e. g., ferns and mosses) preceded the evolution of PHYA. Seed plant phytochromes translocate into the nucleus and regulate gene expression. By contrast, there has been little evidence of a nuclear localization and function of cryptogam phytochromes. Here, we identified responses to FR light in cryptogams, which are highly reminiscent of PHYA signaling in seed plants. In the moss Physcomitrella patens and the fern Adiantum capillus-veneris, phytochromes accumulate in the nucleus in response to light. Although P. patens phytochromes evolved independently of PHYA, we have found that one clade of P. patens phytochromes exhibits the molecular properties of PHYA. We suggest that HIR-like responses had evolved in the last common ancestor of modern seed plants and cryptogams and that HIR signaling is more ancient than PHYA. Thus, other phytochromes in seed plants may have lost the capacity to mediate HIRs during evolution, rather than that PHYA acquired it.