In response to partial plant shading, the lack of phytochrome A does not directly induce leaf senescence but alters the fine-tuning of chlorophyll biosynthesis.
In response to partial plant shading, the lack of phytochrome A does not directly induce leaf senescence but alters the fine-tuning of chlorophyll biosynthesis.
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DOI：
10.1093/jxb/eru060
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发表时间：
2014-07
影响因子：
6.9
通讯作者：
Keech O
中科院分区：
文献类型：
--
作者：
Brouwer B;Gardeström P;Keech O
在部分遮荫植物中，光敏色素A有助于调节遮荫叶片的光合作用，但不直接参与叶片衰老的诱导光敏色素被认为是直接控制叶片衰老的诱导，但其信号转导和分子机制尚不清楚。在本研究中，一个生理生态学的方法被用来建立光敏色素信号和生理过程诱导叶片衰老响应遮荫之间的功能连接。对于遮荫，重要的是要区分完全遮荫和部分遮荫，在此期间，要么整个植物或只有一部分被遮荫。它首先表明，在这里，而PHYB是需要保持叶绿素含量在一个完全遮荫的植物，只有PHYA参与维持叶叶绿素含量响应部分植物遮荫。第二，它表明，叶片黄化与phyA突变体植物中的强部分遮光实际上与叶绿素的生物合成减少，而不是增加其降解。第三，它表明，在强烈阴影phyA突变体叶片叶绿素的生物合成减少的生理影响是伴随着降低的能力，以调整光补偿点。然而，在phyA突变体植物中增加的叶片黄化并不伴随着衰老特异性分子标记的增加，这反对PHYA在诱导叶片衰老中响应于部分遮荫的直接作用。总之，它建议，PHYA，而不是PHYB，是必不可少的微调响应部分遮荫叶绿素生物合成途径。反过来，这种机制允许遮荫叶片调整其光合机制，以非常低的辐照度，从而保持正碳平衡，抑制诱导叶片衰老，这可能会发生在长时间的遮荫。
In partially shaded plants, phytochrome A contributes to the adjustment of photosynthesis in shaded leaves but is not directly involved in the induction of leaf senescence Phytochrome is thought to control the induction of leaf senescence directly, however, the signalling and molecular mechanisms remain unclear. In the present study, an ecophysiological approach was used to establish a functional connection between phytochrome signalling and the physiological processes underlying the induction of leaf senescence in response to shade. With shade it is important to distinguish between complete and partial shading, during which either the whole or only a part of the plant is shaded, respectively. It is first shown here that, while PHYB is required to maintain chlorophyll content in a completely shaded plant, only PHYA is involved in maintaining the leaf chlorophyll content in response to partial plant shading. Second, it is shown that leaf yellowing associated with strong partial shading in phyA-mutant plants actually correlates to a decreased biosynthesis of chlorophyll rather than to an increase of its degradation. Third, it is shown that the physiological impact of this decreased biosynthesis of chlorophyll in strongly shaded phyA-mutant leaves is accompanied by a decreased capacity to adjust the Light Compensation Point. However, the increased leaf yellowing in phyA-mutant plants is not accompanied by an increase of senescence-specific molecular markers, which argues against a direct role of PHYA in inducing leaf senescence in response to partial shade. In conclusion, it is proposed that PHYA, but not PHYB, is essential for fine-tuning the chlorophyll biosynthetic pathway in response to partial shading. In turn, this mechanism allows the shaded leaf to adjust its photosynthetic machinery to very low irradiances, thus maintaining a positive carbon balance and repressing the induction of leaf senescence, which can occur under prolonged periods of shade.
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影响因子：
11.6
作者：
Aukerman, MJ;Hirschfeld, M;Sharrock, RA
通讯作者：
Sharrock, RA
影响因子：
7.4
作者：
Keech, Olivier;Pesquet, Edouard;Gardestrom, Per
通讯作者：
Gardestrom, Per
影响因子：
7.4
作者：
DEGREEF, J;BUTLER, WL;FREDERIC.H
通讯作者：
FREDERIC.H
影响因子：
6.4
作者：
LOHMAN, KN;GAN, SS;AMASINO, RM
通讯作者：
AMASINO, RM
影响因子：
3.9
作者：
Masclaux-Daubresse, C.;Reisdorf-Cren, M.;Orsel, M.
通讯作者：
Orsel, M.