Department of Biology, Duke University, Durham, NC 27705, USA.
Curr Biol. 2011 May 10;21(9):R338-45. doi: 10.1016/j.cub.2011.02.036.
Bioactive gibberellins (GAs) are diterpene phytohormones that modulate growth and development throughout the whole life cycle of the flowering plant. Impressive advances have been made in elucidating the GA pathway with the cloning and characterization of genes encoding most GA biosynthesis and catabolism enzymes, GA receptors (GIBBERELLIN INSENSITIVE DWARF1, GID1) and early GA signaling components. Recent biochemical, genetic and structural analyses demonstrate that GA de-represses its signaling pathway by GID1-induced degradation of DELLA proteins, which are master growth repressors, via a ubiquitin-proteasome pathway. Multiple endogenous signals and environmental cues also interact with the GA-GID1-DELLA regulatory module by affecting the expression of GA metabolism genes, and hence GA content and DELLA levels. Importantly, DELLA integrates different signaling activities by direct protein-protein interaction with multiple key regulatory proteins from other pathways. Comparative studies suggest that the functional GA-GID1-DELLA module is highly conserved among vascular plants, but not in the bryophytes. Interestingly, differentiation of the moss Physcomitrella patens is regulated by as yet unidentified ent-kaurene-derived diterpenes, which are distinct from the common active GAs in vascular plants.
生物活性赤霉素（GAs）是调节植物整个生命周期生长和发育的二萜植物激素。随着编码大多数 GA 生物合成和分解代谢酶、GA 受体（GIBBERELLIN INSENSITIVE DWARF1、GID1）和早期 GA 信号成分的基因的克隆和特征描述，GA 途径的阐明取得了令人瞩目的进展。最近的生化、遗传和结构分析表明，GA 通过 GID1 诱导的 DELLA 蛋白降解来解除其信号通路的抑制，DELLA 蛋白是主要的生长抑制剂，通过泛素-蛋白酶体途径进行。多种内源性信号和环境线索也通过影响 GA 代谢基因的表达，从而影响 GA 含量和 DELLA 水平，与 GA-GID1-DELLA 调控模块相互作用。重要的是，DELLA 通过与来自其他途径的多个关键调节蛋白的直接蛋白-蛋白相互作用来整合不同的信号活性。比较研究表明，功能上的 GA-GID1-DELLA 模块在维管植物中高度保守，但在苔藓植物中则不然。有趣的是，藓类植物 Physcomitrella patens 的分化受尚未鉴定的、来自贝壳杉烯的二萜类物质调节，这些物质与维管植物中常见的活性 GA 不同。
