Hennig L, Büche C, Eichenberg K, Schäfer E
Institut für Biologie II, Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Plant Physiol. 1999 Oct;121(2):571-7. doi: 10.1104/pp.121.2.571.
The dynamic behavior of phytochrome A (phyA) in seedlings of the model plant Arabidopsis was examined by in vivo spectroscopy and by western and northern blotting. Rapid accumulation of phyA was observed, reaching a steady state after 3 d. Both red and far-red light initiated a rapid destruction of the far-red-light-absorbing form of phytochrome (Pfr); the apparent half-life was only 4-fold longer in far-red than in red light. Furthermore, the Pfr-induced destruction of the red-light-absorbing form of phytochrome (Pr) of phyA occurred in darkness with a rate identical to that of Pfr destruction. A 2-fold decrease in mRNA abundance was observed after irradiation, irrespective of the applied light quality. However, reaccumulation occurred rapidly after far-red but slowly after red irradiation, indicating different modes of regulation of phytochrome expression after light-dark transitions depending on the light quality of the preceding irradiation. The wavelength dependency of the destruction rates was distinct from that of mustard, a close relative of Arabidopsis, and was explained on the basis of Pfr-induced Pr destruction and a simple kinetic two-step model. No dark reversion was detectable in the destruction kinetics after a red pulse. From these data we conclude that Arabidopsis phyA differs significantly in several aspects from other dicot phytochromes.
通过体内光谱法以及蛋白质免疫印迹和Northern印迹法，对模式植物拟南芥幼苗中光敏色素A（phyA）的动态行为进行了研究。观察到phyA迅速积累，3天后达到稳定状态。红光和远红光均能引发光敏色素远红光吸收形式（Pfr）的快速降解；其表观半衰期在远红光下仅比在红光下长4倍。此外，Pfr诱导的phyA的红光吸收形式（Pr）的降解在黑暗中发生，其速率与Pfr降解速率相同。照射后，无论所用光质如何，mRNA丰度均下降了2倍。然而，远红光照射后phyA迅速重新积累，而红光照射后则缓慢重新积累，这表明光暗转换后光敏色素表达的调控模式因先前照射的光质而异。降解速率的波长依赖性与拟南芥的近缘种芥菜不同，并基于Pfr诱导的Pr降解和一个简单的动力学两步模型进行了解释。红光脉冲后，在降解动力学中未检测到暗逆转。根据这些数据，我们得出结论，拟南芥phyA在几个方面与其他双子叶植物光敏色素有显著差异。
