Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction.
Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction.
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发表时间：
1999-05
期刊：
影响因子：
4.6
通讯作者：
T. Mockler;Hongwei Guo;Hongyun Yang;Hien T. T. Duong-Hien-T.-T.-Duong-49027206;Chentao Lin
中科院分区：
文献类型：
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作者：
T. Mockler;Hongwei Guo;Hongyun Yang;Hien T. T. Duong-Hien-T.-T.-Duong-49027206;Chentao Lin
拟南芥光感受器cry 1、cry 2和phyB在开花时间的调控中发挥重要作用，但其分子机制尚不清楚。我们以前假设，phyB介导的红光抑制花的起始和cry 2介导的phyB功能的蓝光抑制。对cry 2/phyB双突变体的研究为支持这一假设提供了直接证据。利用cry 2/cry 1双突变体进一步研究了隐花色素在成花诱导中的作用。cry 2/cry 1双突变体在单色蓝光下表现出延迟开花，而单基因cry 1和cry 2突变体在蓝光下均不表现出延迟开花。这一结果表明，除了phyB依赖的功能，cry 2还与cry 1冗余地起作用，以phyB独立的方式促进花的起始。为了了解光感受器如何调节从营养生长到生殖发育的过渡，我们研究了蓝光和红光顺序照射对植物开花时间的影响。我们发现，植物发育过程中存在一个光质敏感期，在此期间，光质对开花时间有着深刻的影响。在此发育阶段之后，即萌发后约第1天至第7天之间，植物致力于成花，并且光的质量对开花时间几乎没有影响。无论是PHYB基因突变或两个的PHYB 1和PHYB 2基因导致的损失的光质量敏感期表现在花发育。由植物对光质的敏感性定义的花转变的承诺时间与先前由植物对光量的敏感性揭示的花序发育的承诺时间-光周期一致。因此，导致开花承诺的发育机制似乎是光感受器拮抗作用的直接目标。
The Arabidopsis photoreceptors cry1, cry2 and phyB are known to play roles in the regulation of flowering time, for which the molecular mechanisms remain unclear. We have previously hypothesized that phyB mediates a red-light inhibition of floral initiation and cry2 mediates a blue-light inhibition of the phyB function. Studies of the cry2/phyB double mutant provide direct evidence in support of this hypothesis. The function of cryptochromes in floral induction was further investigated using the cry2/cry1 double mutants. The cry2/cry1 double mutants showed delayed flowering in monochromatic blue light, whereas neither monogenic cry1 nor cry2 mutant exhibited late flowering in blue light. This result suggests that, in addition to the phyB-dependent function, cry2 also acts redundantly with cry1 to promote floral initiation in a phyB-independent manner. To understand how photoreceptors regulate the transition from vegetative growth to reproductive development, we examined the effect of sequential illumination by blue light and red light on the flowering time of plants. We found that there was a light-quality-sensitive phase of plant development, during which the quality of light exerts a profound influence on flowering time. After this developmental stage, which is between approximately day-1 to day-7 post germination, plants are committed to floral initiation and the quality of light has little effect on the flowering time. Mutations in either the PHYB gene or both the CRY1 and CRY2 genes resulted in the loss of the light-quality-sensitive phase manifested during floral development. The commitment time of floral transition, defined by a plant's sensitivity to light quality, coincides with the commitment time of inflorescence development revealed previously by a plant's sensitivity to light quantity - the photoperiod. Therefore, the developmental mechanism resulting in the commitment to flowering appears to be the direct target of the antagonistic actions of the photoreceptors.