Phytochrome B Nuclear Bodies Respond to the Low Red to Far-Red Ratio and to the Reduced Irradiance of Canopy Shade in Arabidopsis
Phytochrome B Nuclear Bodies Respond to the Low Red to Far-Red Ratio and to the Reduced Irradiance of Canopy Shade in Arabidopsis
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DOI：
10.1104/pp.114.242438
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发表时间：
2014-08-01
期刊：
影响因子：
7.4
通讯作者：
Jose Casal, Jorge
中科院分区：
文献类型：
--
作者：
Ariel Trupkin, Santiago;Legris, Martina;Jose Casal, Jorge
目前的共识是植物对遮荫的响应涉及光敏色素B （phytochrome B, phyB）对低红远红比（R:FRs）的感知，这导致光敏色素相互作用因子（phytochrome INTERACTING FACTORs, PIFs）直接激活生长素合成基因。除了对R: fr的影响外，遮荫还会降低辐照度，但遮荫引起的辐照度下降是否会影响phyB活性尚未得到证实。为了解决这一问题，我们研究了辐照度和R:FRs是否对光生植物叶柄细胞中phyB的核分布有相似的影响。在高辐照度白光下，phyB形成较大的核体。在不改变R:FRs的情况下降低辐照度或通过添加远红光降低R:FRs导致含有phyB的小核体的出现。大的核体仍然存在，但同时直径有所减小。在恢复到高辐照度和高R:FRs后，小核体的出现是快速、稳定和可逆的。高水平的红光而不是蓝光足以抑制小phyB核体的形成。在自然冠层的范围内，甚至在相对较低的R:FRs下，辐照度是有效的。在phyB和pif突变体中，降低辐照度对叶片发育不良的促进作用被削弱，正如之前报道的对R:FRs的反应一样。生长素相关基因的表达在低R:FRs和低辐照下表现出相似的响应层次。我们认为phyB不仅能感知低R:FRs，还能感知阴影的低辐照度。
The current consensus is that plant responses to canopy shade involve the perception of low red to far-red ratios (R:FRs) by phytochrome B (phyB), which leads to the direct activation of auxin synthesis genes by PHYTOCHROME INTERACTING FACTORs (PIFs). In addition to its effect on R:FRs, shade also reduces irradiance, but whether shade-induced drops in irradiance affect phyB activity has not been demonstrated. To address this issue, we investigated whether irradiance and R:FRs have similar effects on the nuclear distribution of phyB in petiole cells of light-grown plants. Under high-irradiance white light, phyB formed large nuclear bodies. Lowering irradiance without changing R:FRs or lowering R:FRs by adding far-red light led to the appearance of small nuclear bodies containing phyB. Large nuclear bodies remained but with some concomitant reduction in diameter. The appearance of small nuclear bodies was rapid, stable, and reversible upon the return to high irradiance and high R:FRs. High levels of red light but not of blue light were enough to restrain the formation of small phyB nuclear bodies. Irradiance was effective within the range found in natural canopies and even under relatively low R:FRs. The promotion of leaf hyponasty by lowering irradiance was impaired in phyB and pif mutants, as previously reported for the response to R:FRs. The expression of auxin-related genes showed a similar hierarchy of response to low R:FRs and low irradiance. We propose that phyB is able to perceive not only the low R:FRs, but also the low irradiance of shade.