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PHYTOCHROME INTERACTING FACTOR8 Inhibits Phytochrome A-Mediated Far-Red Light Responses in Arabidopsis.
The Plant Cell ( IF 10.0 ) Pub Date : 2019-11-15 , DOI: 10.1105/tpc.19.00515
Jeonghwa Oh 1 , Eunae Park 1 , Kijong Song 1 , Gabyong Bae 1 , Giltsu Choi 2
Affiliation  

PHYTOCHROME INTERACTING FACTORs (PIFs) are a group of basic helix-loop-helix (bHLH) transcription factors that repress plant light responses. PIF8 is one of the less-characterized Arabidopsis (Arabidopsis thaliana) PIFs, whose putative orthologs are conserved in other plant species. PIF8 possesses a bHLH motif and an active phytochrome B motif but not an active phytochrome A motif. Consistent with this motif composition, PIF8 binds to G-box elements and interacts with the Pfr form of phyB but only very weakly, if at all, with that of phyA. PIF8 differs, however, from other PIFs in its protein accumulation pattern and functional roles in different light conditions. First, PIF8 inhibits phyA-induced seed germination, suppression of hypocotyl elongation, and randomization of hypocotyl growth orientation in far-red light, but it does not inhibit phyB-induced red light responses. Second, PIF8 protein accumulates more in far-red light than in darkness or red light. This is distinct from the pattern observed with PIF3, which accumulates more in darkness. This PIF8 accumulation pattern requires degradation of PIF8 by CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) in darkness, inhibition of COP1 by phyA in far-red light, and promotion of PIF8 degradation by phyB in red light. Together, our results indicate that PIF8 is a genuine PIF that represses phyA-mediated light responses.

中文翻译:

植物色素相互作用因子8抑制拟南芥中植物色素A介导的远红光响应。

植物染色体相互作用因子(PIF)是一组抑制植物光反应的基本螺旋-环-螺旋(bHLH)转录因子。PIF8是特征较少的拟南芥(Arabidopsis thaliana)PIF之一,其推定的直系同源基因在其他植物物种中均是保守的。PIF8具有bHLH基序和活性的植物色素B基序,但不具有活性的植物色素A基序。与该基序组成一致,PIF8与G-box元件结合并与phyB的Pfr形式相互作用,但与phyA的相互作用非常弱(如果有的话)。但是,PIF8与其他PIF的不同之处在于其蛋白质积累模式和在不同光照条件下的功能作用。首先,PIF8抑制phyA诱导的种子发芽,抑制下胚轴伸长,并在远红外光下抑制下胚轴生长方向,但它不抑制phyB诱导的红光响应。其次,PIF8蛋白在远红光下比在黑暗或红光下积累更多。这与PIF3观察到的模式不同,后者在黑暗中会积累更多。这种PIF8积累模式需要在黑暗中通过本构性光生化酶1(COP1)降解PIF8,在远红光下通过phyA抑制COP1,并在红色光下通过phyB促进PIF8降解。总之,我们的结果表明PIF8是一种真正的PIF,可以抑制phyA介导的光反应。这种PIF8积累模式需要在黑暗中通过本构性光生化酶1(COP1)降解PIF8,在远红光下通过phyA抑制COP1,并在红色光下通过phyB促进PIF8降解。总之,我们的结果表明PIF8是一种真正的PIF,可以抑制phyA介导的光反应。这种PIF8积累模式需要在黑暗中通过本构性光生化酶1(COP1)降解PIF8,在远红光下通过phyA抑制COP1,并在红色光下通过phyB促进PIF8降解。总之,我们的结果表明PIF8是一种真正的PIF,可以抑制phyA介导的光反应。
更新日期:2020-01-11
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