Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark.
Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark.
复制标题
光敏色素 B 的光体定位与黑暗中下胚轴伸长的长期且光依赖性抑制密切相关。
DOI：
10.1104/pp.114.236661
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发表时间：
2014
期刊：
影响因子：
7.4
通讯作者：
Chen,Meng
中科院分区：
文献类型：
--
作者：
VanBuskirk,EliseK;Reddy,AmitK;Nagatani,Akira;Chen,Meng
拟南芥光敏色素B（phyB）与绿色荧光蛋白（PBG）融合蛋白的光体定位与下胚轴伸长的光抑制密切相关。然而，氨基末端的一半的phyB融合到绿色荧光蛋白（NGB）是光过敏，尽管它不能本地化的光体。因此，光体在调节下胚轴生长中的意义仍然存在争议。越来越多的证据表明，在昼夜条件下，光活化的phyB持续到黑暗中抑制下胚轴伸长。在这里，我们研究是否光体参与抑制下胚轴生长在黑暗中通过比较PBGandNGBlines后，红光到黑暗的过渡。令人惊讶的是，在从10 μmol m−2s− 1红光过渡到黑暗后，PBG抑制下胚轴伸长的时间是NGB的三倍。下胚轴细胞核中光体的分解与生长促进转录因子光敏色素相互作用因子3（PIF3）的积累密切相关。在光暗转换之前通过降低光强度或添加单色远红光处理来使光体失稳，导致更快的PIF3积累和PBG中下胚轴生长抑制能力的显著降低。相比之下，NGB在PIF3降解方面有缺陷，并且其下胚轴在黑暗中的生长几乎对光照条件的变化没有反应。总之，我们的研究结果支持的模型，光体所需的长期，光依赖性抑制下胚轴伸长在黑暗中抑制PIF3积累和稳定的远红光吸收形式的phyB。我们的研究表明，phyB的光体定位模式可以作为指导性的线索，控制光依赖的光形态发生反应在黑暗中。
Photobody localization of Arabidopsis (Arabidopsis thaliana) phytochrome B (phyB) fused to green fluorescent protein (PBG) correlates closely with the photoinhibition of hypocotyl elongation. However, the amino-terminal half of phyB fused to green fluorescent protein (NGB) is hypersensitive to light despite its inability to localize to photobodies. Therefore, the significance of photobodies in regulating hypocotyl growth remains debatable. Accumulating evidence indicates that under diurnal conditions, photoactivated phyB persists into darkness to inhibit hypocotyl elongation. Here, we examine whether photobodies are involved in inhibiting hypocotyl growth in darkness by comparing thePBGandNGBlines after the red light-to-dark transition. Surprisingly, after the transition from 10 μmol m−2s−1red light to darkness,PBGinhibits hypocotyl elongation three times longer thanNGB. The disassembly of photobodies inPBGhypocotyl nuclei correlates tightly with the accumulation of the growth-promoting transcription factor PHYTOCHROME-INTERACTING FACTOR3 (PIF3). Destabilizing photobodies by either decreasing the light intensity or adding monochromatic far-red light treatment before the light-to-dark transition leads to faster PIF3 accumulation and a dramatic reduction in the capacity for hypocotyl growth inhibition inPBG. In contrast,NGBis defective in PIF3 degradation, and its hypocotyl growth in the dark is nearly unresponsive to changes in light conditions. Together, our results support the model that photobodies are required for the prolonged, light-dependent inhibition of hypocotyl elongation in the dark by repressing PIF3 accumulation and by stabilizing the far-red light-absorbing form of phyB. Our study suggests that photobody localization patterns of phyB could serve as instructive cues that control light-dependent photomorphogenetic responses in the dark.