Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factors
Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factors
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DOI：
10.1073/pnas.0812219106
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发表时间：
2009-05-05
影响因子：
11.1
通讯作者：
Choi, Giltsu
中科院分区：
文献类型：
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作者：
Shin, Jieun;Kim, Keunhwa;Choi, Giltsu
PIF 3是光敏色素相互作用的碱性螺旋-环-螺旋转录因子，其负调节光响应，包括下胚轴伸长、子叶打开和下胚轴负向重力性。然而，PIF 3在叶绿素生物合成中的作用尚未明确。在这里，我们表明，PIF 3也负调节叶绿素的生物合成抑制生物合成基因在黑暗中。与基因表达模式一致，黄化的pif 3突变体积累了更高量的原叶绿素，并且当转移到光照下时严重漂白。pif 3的光漂白表型可以被gun 5突变抑制，并被GUN 5的过表达所模仿。当4个负光敏色素相互作用蛋白基因（PIF 1，PIF 3，PIF 4，和PIF 5）突变，产生的四重突变体幼苗表现出组成型光形态发生表型，包括短下胚轴，开放子叶，并在黑暗中破坏下胚轴向重力性。微阵列分析进一步证实，黑暗生长的四倍体突变体具有类似于红光生长的WT的基因表达模式。总之，我们的数据表明，4光敏色素相互作用蛋白所需的skotomorphogenesis和光敏色素激活光形态通过抑制这些因素。
PIF3 is a phytochrome-interacting basic helix-loop-helix transcription factor that negatively regulates light responses, including hypocotyl elongation, cotyledon opening, and hypocotyl negative gravitropism. However, the role of PIF3 in chlorophyll biosynthesis has not been clearly defined. Here, we show that PIF3 also negatively regulates chlorophyll biosynthesis by repressing biosynthetic genes in the dark. Consistent with the gene expression patterns, the etiolated pif3 mutant accumulated a higher amount of protochlorophyllide and was bleached severely when transferred into light. The photobleaching phenotype of pif3 could be suppressed by the gun5 mutation and mimicked by overexpression of GUN5. When 4 negative phytochrome-interacting protein genes (PIF1, PIF3, PIF4, and PIF5) were mutated, the resulting quadruple mutant seedlings displayed constitutive photomorphogenic phenotypes, including short hypocotyls, open cotyledons, and disrupted hypocotyl gravitropism in the dark. Microarray analysis further confirmed that the dark-grown quadruple mutant has a gene expression pattern similar to that of red light-grown WT. Together, our data indicate that 4 phytochrome-interacting proteins are required for skotomorphogenesis and phytochromes activate photomorphogenesis by inhibiting these factors.