Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland.
Curr Biol. 2011 May 10;21(9):R365-73. doi: 10.1016/j.cub.2011.03.013.
The remarkable plasticity of plant ontogeny is shaped by hormone pathways, which not only orchestrate intrinsic developmental programs, but also convey environmental inputs. Several classes of plant hormones exist, and among them auxin, brassinosteroid and gibberellin are central for the regulation of growth in general and of cell elongation in particular. Various growth phenomena can be modulated by each of the three hormones, in a sometimes synergistic fashion, suggesting physiological redundancy and/or crosstalk between the different pathways. Whether this means that they target a common and unique transcriptome module, or rather separate growth-promoting transcriptome modules, remains unclear, however. Nevertheless, while surprisingly few molecular mediators of direct crosstalk in the proper sense have been isolated, evidence is accumulating for complex cross-regulatory relations between hormone pathways at the level of transcription, as exemplified in root meristem growth. The growing number of available genome sequences from the green lineage offers first glimpses at the evolution of hormone pathways, which can aid in understanding the multiple relationships observed between these pathways in angiosperms. The available analyses suggest that auxin, gibberellin and brassinosteroid signalling arose during land plant evolution in this order, correlating with increased morphological complexity and possibly conferring increased developmental flexibility.
植物个体发育的显著可塑性是由激素途径塑造的，这些途径不仅协调内在的发育程序，还传递环境输入。存在几类植物激素，其中生长素、油菜素内酯和赤霉素对于一般的生长和细胞伸长的调节是至关重要的。这三种激素中的每一种都可以通过有时协同的方式调节各种生长现象，这表明不同途径之间存在生理冗余和/或串扰。然而，目前尚不清楚这是否意味着它们针对一个共同的和独特的转录组模块，或者是不同的促进生长的转录组模块。尽管如此，虽然已经分离出很少的直接串扰的分子介质，但在转录水平上，激素途径之间存在复杂的交叉调控关系的证据正在积累，例如在根分生组织生长中。来自绿色谱系的越来越多的可用基因组序列提供了激素途径进化的初步见解，这有助于理解在被子植物中观察到的这些途径之间的多种关系。现有的分析表明，生长素、赤霉素和油菜素内酯信号在陆生植物进化过程中依次出现，与形态复杂性的增加相关，并可能赋予更高的发育灵活性。
