Phytochrome A enhances the promotion of hypocotyl growth caused by reductions in levels of phytochrome B in its far-red-light-absorbing form in light-grown Arabidopsis thaliana
Phytochrome A enhances the promotion of hypocotyl growth caused by reductions in levels of phytochrome B in its far-red-light-absorbing form in light-grown Arabidopsis thaliana
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DOI：
10.1104/pp.112.3.965
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发表时间：
1996-11-01
期刊：
影响因子：
7.4
通讯作者：
Casal, JJ
中科院分区：
文献类型：
--
作者：
Casal, JJ
我们试图确定光敏色素B(PhyB)介导的对红光(R)/远红光(FR)比率的反应是否受到光敏色素A(PhyA)活性的影响。在黑暗中，延迟到暗期的FR脉冲在促进下胚轴生长方面不如日终(EOD)FR有效。在白光周期结束和FR脉冲之间插入白光减去蓝光而不是黑暗，足以维持野生型(WT)幼苗对FR-光吸收形式PhyB减少的响应，但在PhyA突变体中则不是。与EOD-R相比，在拟南芥、黄瓜、芥菜、向日葵、烟草和番茄中，整夜每小时提供一次的R+FR脉冲对茎的生长的促进作用要强于单一的EOD-R+FR脉冲，而在拟南芥和番茄的金色突变体中则没有。拟南芥的WT幼苗对一系列高的EOD R/FR比率做出反应，而PhyA突变体需要更大程度地降低EOD R/FR比率。在光照条件下，拟南芥Phya幼苗对周围植被的“预警”信号没有反应，下胚轴生长促进作用发生在较高密度的植株上。因此，在一系列光照条件下，WT幼苗对R/FR比值降低的敏感性或响应性大于Phya幼苗。因此，提出了一种PhyA的产物，以增强光生长幼苗对FR光吸收形式的PhyB减少的下胚轴生长的反应。
We sought to determine if phytochrome B (phyB)-mediated responses to the red light (R)/far-red light (FR) ratio are affected by phytochrome A (phyA) activity in light-grown seedlings of Arabidopsis thaliana. Pulses of FR delayed into the dark period were less effective than end-of-day (EOD) FR in promoting hypocotyl growth over a given period in darkness. White light minus blue light interposed instead of darkness between the end of the white-light photoperiod and the FR pulse was sufficient to maintain responsivity to the decrease in phyB in FR-light-absorbing form in wild-type (WT) seedlings, but not in the phyA mutant. Compared with EOD R, hourly R+FR pulses provided throughout the night caused a stronger promotion of stem growth than a single EOD R+FR pulse in WT Arabidopsis, cucumber, mustard, sunflower, tobacco, and tomato, but not in phyA Arabidopsis or in the aurea mutant of tomato. WT seedlings of Arabidopsis responded to a range of high EOD R/FR ratios, whereas the phyA mutant required stronger reductions in the EOD R/FR ratio. In sunlight, phyA seedlings of Arabidopsis showed no response to the ''early warning'' signals of neighboring vegetation, and hypocotyl-growth promotion occurred at higher plant densities than in the WT. Thus, under a series of light conditions, the sensitivity or responsivity to reductions in the R/FR ratio were larger in WT than in phyA seedlings. A product of phyA is therefore proposed to enhance the hypocotyl-growth response to decreases in phyB in FR-light-absorbing form in light-grown seedlings.