Müssig C
Universität Potsdam-Genetik, Karl-Liebknecht-Strasse 24 - 25, Haus 26, 14476 Golm, Germany.
Plant Biol (Stuttg). 2005 Mar;7(2):110-7. doi: 10.1055/s-2005-837493.
Brassinosteroids (BRs) are highly potent growth-promoting sterol derivatives. BR-deficient or BR-insensitive mutants display dwarfism. Whole plants and excised tissues have been used to analyse the mechanisms involved in BR-promoted growth. BR stimulates cell elongation and cell division, and BR has specific effects on differentiation. Underlying physiological pathways include modification of cell wall properties, effects on carbohydrate assimilation and allocation, and control of aquaporin activities. BR apparently coordinates and integrates diverse processes required for growth, partly via interactions with other phytohormones setting the frame for BR responses. Ultimately, BR-promoted growth is mediated through genomic pathways. Positive regulators of the BR response (such as BZR1 and BES1) and putative downstream components (such as EXO) are involved in the regulation of BR-responsive genes and growth promotion. BR-responsive genes have been identified in several plant species. However, causal links between physiological effects and changes of transcript patterns, for the most part, are still unresolved. This review focuses on physiology and molecular mechanisms underlying BR-promoted growth in the different plant organs. Interactions with other phytohormones are discussed.
油菜素甾醇（BRs）是一类具有高效促生长活性的甾醇衍生物。BR缺乏或不敏感的突变体表现出矮化现象。完整植株和离体组织已被用于分析BR促进生长所涉及的机制。BR能刺激细胞伸长和细胞分裂，且对分化有特定作用。其潜在的生理途径包括细胞壁特性的改变、对碳水化合物同化和分配的影响以及对水通道蛋白活性的调控。BR显然通过与其他植物激素的相互作用来协调和整合生长所需的各种过程，这些相互作用为BR反应奠定了基础。最终，BR促进生长是通过基因组途径介导的。BR反应的正向调节因子（如BZR1和BES1）以及假定的下游组分（如EXO）参与BR反应基因的调控和生长促进。在几种植物物种中已鉴定出BR反应基因。然而，生理效应与转录模式变化之间的因果联系在很大程度上仍未得到解决。本综述重点关注不同植物器官中BR促进生长的生理学和分子机制，并讨论了其与其他植物激素的相互作用。
