Evans L T, Heide O M, King R W
CSIRO, Division of Plant Industry, G.P.O. Box 1600, Canberra, A.C.T. 2601, Australia.
Plant Physiol. 1986 Apr;80(4):1025-9. doi: 10.1104/pp.80.4.1025.
The semidian ( approximately 12 h) periodicity in the effect of far-red (FR) interruptions of the light period preceding inductive darkness on flowering in Pharbitis nil appears to be mediated by phytochrome: (a) promotion by interruptions 2 hours before inductive darkness (-2 hours) and inhibition at -8 hours are greater the higher the proportion of FR/R+FR during the interruption; (b) brief FR exposures followed by darkness are even more effective than FR throughout; (c) the effect of brief FR is reversed by subsequent R; (d) R interruptions of an FR background are most promotive at -8 hours, when FR is most inhibitory. Promotive FR interruptions at -2 or -14 hours shorten the critical dark period whereas inhibitory FR interruptions at -8 hours lengthen it. We conclude that the semidian rhythm is controlled by a ;timing pool' of phytochrome FR absorbing form (Pfr) which disappears rapidly in darkness: four different estimates from our experiments indicate that Pfr was reduced to the level set by FR within 20 to 45 minutes in darkness. However, flowering may also be influenced by a ;metabolic pool' of Pfr with a delayed loss in darkness, the time of which can be advanced or retarded by shifting the semidian rhythm.
在诱导性暗期之前的光期进行远红光（FR）中断处理对牵牛花花芽分化的影响中，半日（约12小时）周期性似乎由光敏色素介导：（a）在诱导性暗期前2小时（-2小时）进行中断处理有促进作用，而在-8小时进行中断处理有抑制作用，中断期间FR/R+FR的比例越高，这种促进和抑制作用就越明显；（b）短暂的FR照射后紧接着黑暗处理比全程照射FR更有效；（c）短暂的FR处理效果会被随后的红光（R）逆转；（d）在FR背景下进行R中断处理，在-8小时时促进作用最强，而此时FR的抑制作用最强。在-2或-14小时进行促进性的FR中断处理会缩短临界暗期，而在-8小时进行抑制性的FR中断处理会延长临界暗期。我们得出结论，半日节律由光敏色素远红光吸收型（Pfr）的一个“定时库”控制，该定时库在黑暗中迅速消失：我们实验中的四种不同估计表明，在黑暗中，Pfr在20至45分钟内降至由FR设定的水平。然而，花芽分化也可能受Pfr“代谢库”的影响，其在黑暗中的损失有延迟，通过改变半日节律可提前或推迟其消失时间。
