Sineshchekov V, Belyaeva O, Sudnitsin A
Biology Department of the M.V. Lomonosov Moscow State University, Moscow 119899, Russia.
J Photochem Photobiol B. 2004 Mar 19;74(1):47-54. doi: 10.1016/j.jphotobiol.2004.02.001.
It is well-documented that phytochrome A (phyA) down-regulates the synthesis of NADPH:protochlorophyllide (Pchlide) oxidoreductase and active Pchlide(655) under far-red light (FR). In this work, we demonstrate that phyA can up-regulate the synthesis of Pchlide(655) under FR as well and that its sign and extent depend on plant species and tissue. With the use of fluorescence spectroscopy, it was found that [Pchlide(655)] in the upper stems of FR-grown seedlings of pea and tobacco increased > or =10-fold and much lower in cotyledons or leaves as compared with the dark-grown. In the upper stems of Arabidopsis and tomato, the positive effect of FR was low, 1.2- to 1.5-fold, and the negative effect of FR was seen in cotyledons. In stems of wild-type (WT) tobacco and its line overexpressing full-length oat phyA (FL), we observed gross stimulating effect of FR while in its line overexpressing N-terminally truncated (Delta7-69) oat phyA (NA) it was low. Because WT and FL comprise both native phyA forms, phyA' and phyA", while NA, only phyA", the regulation under FR can be associated with phyA', while phyA" inhibits the action of phyA'. In etiolated seedlings of the NA line, [Pchlide(655)] was much higher than in those of WT and FL suggesting that phyA" may have relation to this enhancement. The regulation of Pchlide(633) in contrast to Pchlide(655) was positive independent of the plant species and tissue.
有充分文献记载，在远红光（FR）条件下，光敏色素A（phyA）会下调NADPH：原叶绿素酸酯（Pchlide）氧化还原酶和活性Pchlide(655)的合成。在本研究中，我们证明phyA在FR条件下也能上调Pchlide(655)的合成，其正负效应及程度取决于植物种类和组织。通过荧光光谱法发现，与黑暗生长的豌豆和烟草幼苗上茎中的[Pchlide(655)]相比，FR处理的幼苗上茎中的[Pchlide(655)]增加了≥10倍，而子叶或叶片中的则低得多。在拟南芥和番茄的上茎中，FR的正向效应较低，为1.2至1.5倍，而在子叶中则观察到FR的负向效应。在野生型（WT）烟草及其过表达全长燕麦phyA（FL）的株系茎中，我们观察到FR有明显的刺激作用，而过表达N端截短（Delta7-69）燕麦phyA（NA）的株系中该效应较低。由于WT和FL包含天然的phyA形式phyA'和phyA"，而NA只包含phyA"，因此FR条件下的调控可能与phyA'有关，而phyA"会抑制phyA'的作用。在NA株系的黄化幼苗中，[Pchlide(655)]比WT和FL株系中的高得多，这表明phyA"可能与这种增强有关。与Pchlide(655)相反。Pchlide(633)的调控与植物种类和组织无关，呈正向调控。
