Casal J J, Boccalandro H
Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
Planta. 1995;197(2):213-8. doi: 10.1007/BF00202639.
A combination of physiological and genetic approaches was used to investigate whether phytochromes and blue light (BL) photoreceptors act in a fully independent manner during photomorphogenesis of Arabidopsis thaliana (L.) Heynh. Wild-type seedlings and phyA, phyB and hy4 mutants were daily exposed to 3 h BL terminated with either a red light (R) or a far-red light (FR) pulse. In wild-type and phyA-mutant seedlings, BL followed by an R pulse inhibited hypocotyl growth and promoted cotyledon unfolding. The effects of BL were reduced if exposure to BL was followed by an FR pulse driving phytochrome to the R-absorbing form (Pr). In the wild type, the effects of R versus FR pulses were small in seedlings not exposed to BL. Thus, maximal responses depended on the presence of both BL and the FR-absorbing form of phytochrome (Pfr) in the subsequent dark period. Impaired responses to BL and to R versus FR pulses were observed in phyB and hy4 mutants. Simultaneous irradiation with orange light indicated that BL, perceived by specific BL photoreceptors (i.e. not by phytochromes), required phytochrome B to display a full effect. These results indicate interdependent co-action between phytochrome B and BL photoreceptors, particularly the HY4 gene product. No synergism between phytochrome A (activated by continuous or pulsed FR) and BL photoreceptors was observed.
采用生理学和遗传学相结合的方法，研究在拟南芥光形态建成过程中，光敏色素和蓝光（BL）光受体是否以完全独立的方式发挥作用。野生型幼苗以及phyA、phyB和hy4突变体幼苗每天接受3小时蓝光照射，随后以红光（R）或远红光（FR）脉冲终止。在野生型和phyA突变体幼苗中，蓝光后接红光脉冲会抑制下胚轴生长并促进子叶展开。如果蓝光照射后接远红光脉冲使光敏色素转变为吸收红光的形式（Pr），蓝光的效应就会减弱。在未接受蓝光照射的野生型幼苗中，红光与远红光脉冲的效应较小。因此，最大反应取决于蓝光的存在以及随后黑暗期吸收远红光形式的光敏色素（Pfr）的存在。在phyB和hy4突变体中观察到对蓝光以及红光与远红光脉冲的反应受损。橙色光的同时照射表明，由特定蓝光光受体感知的蓝光（即不是由光敏色素感知）需要光敏色素B才能发挥完全效应。这些结果表明光敏色素B和蓝光光受体之间存在相互依赖的协同作用，特别是HY4基因产物。未观察到光敏色素A（由连续或脉冲远红光激活）与蓝光光受体之间的协同作用。
