Kramer Susan, Piotrowski Markus, Kuhnemann Frank, Edelmann Hans G
Botanisches Institut der Universität Bonn, Abteilung Molekularbiologie, Kirschallee 1, D-53115 Bonn, Germany.
J Exp Bot. 2003 Dec;54(393):2723-32. doi: 10.1093/jxb/erg310.
A recent study demonstrated that gravi-incompetent coleoptile-less seedlings of rye exhibit gravi-competence after exogenous application of ethylene. Treatments and conditions which induce and interfere with this phenomenon were analysed in more detail. Aminocyclopropane-1-carboxylic acid (ACC) as a precursor of ethylene has similar gravicompetence-inducing effects and also appropriate conditions of light, which strongly enhances ethylene synthesis. Both effects can be inhibited by the ethylene-perception blocking agent methylcyclopropene (MCP) or inhibitors of ethylene synthesis such as aminovinylglycine (AVG), indicating that light exerts its gravicompetence-generating effect via induced/enhanced ethylene synthesis. Gain in gravicompetence is accompanied by the induced/enhanced occurrence of calreticulin and lipoxygenase as detected by 2D-gels and Q-TOFF-analyses. Previously gravicompetent, light-grown coleoptile-less seedlings are characterized by gravi-incompetent growth during subsequent horizontal gravistimulation when perception of ethylene is inhibited by MCP. The results demonstrate that continuous perception of ethylene is an indispensable step, permanently required for the regulation of gravitropic growth in germinating primary shoots of rye, either within the process of graviperception and/or of the transduction of the gravi-signal.
最近的一项研究表明，黑麦无胚芽鞘且重力不敏感的幼苗在施加外源乙烯后会表现出重力敏感性。对诱导和干扰这一现象的处理方法及条件进行了更详细的分析。作为乙烯前体的1-氨基环丙烷-1-羧酸（ACC）具有类似的诱导重力敏感性的作用，光照条件也合适，光照会强烈促进乙烯合成。这两种效应都可被乙烯感知阻断剂甲基环丙烯（MCP）或乙烯合成抑制剂如氨基乙烯基甘氨酸（AVG）抑制，这表明光照通过诱导/增强乙烯合成发挥其产生重力敏感性的作用。通过二维凝胶电泳和Q-TOFF分析检测到，重力敏感性的增加伴随着钙网蛋白和脂氧合酶的诱导/增强出现。先前具有重力敏感性、在光照下生长的无胚芽鞘幼苗，当乙烯感知被MCP抑制时，在随后的水平重力刺激过程中表现出重力不敏感生长。结果表明，持续感知乙烯是黑麦萌发初生根重力生长调节过程中不可或缺的一步，这一步在重力感知过程和/或重力信号转导过程中一直是必需的。
