Teichmann Thomas, Muhr Merlin
Plant Cell Biology, Georg-August-Universität Göttingen, Göttingen Germany.
Front Plant Sci. 2015 Apr 9;6:233. doi: 10.3389/fpls.2015.00233. eCollection 2015.
Plants exhibit phenotypical plasticity. Their general body plan is genetically determined, but plant architecture and branching patterns are variable and can be adjusted to the prevailing environmental conditions. The modular design of the plant facilitates such morphological adaptations. The prerequisite for the formation of a branch is the initiation of an axillary meristem. Here, we review the current knowledge about this process. After its establishment, the meristem can develop into a bud which can either become dormant or grow out and form a branch. Many endogenous factors, such as photoassimilate availability, and exogenous factors like nutrient availability or shading, have to be integrated in the decision whether a branch is formed. The underlying regulatory network is complex and involves phytohormones and transcription factors. The hormone auxin is derived from the shoot apex and inhibits bud outgrowth indirectly in a process termed apical dominance. Strigolactones appear to modulate apical dominance by modification of auxin fluxes. Furthermore, the transcription factor BRANCHED1 plays a central role. The exact interplay of all these factors still remains obscure and there are alternative models. We discuss recent findings in the field along with the major models. Plant architecture is economically significant because it affects important traits of crop and ornamental plants, as well as trees cultivated in forestry or on short rotation coppices. As a consequence, plant architecture has been modified during plant domestication. Research revealed that only few key genes have been the target of selection during plant domestication and in breeding programs. Here, we discuss such findings on the basis of various examples. Architectural ideotypes that provide advantages for crop plant management and yield are described. We also outline the potential of breeding and biotechnological approaches to further modify and improve plant architecture for economic needs.
植物表现出表型可塑性。它们的总体形态由基因决定，但植物的结构和分枝模式是可变的，并且可以根据当前的环境条件进行调整。植物的模块化设计有助于这种形态适应。形成分枝的前提是腋生分生组织的起始。在此，我们综述了关于这一过程的现有知识。分生组织形成后，可发育成芽，芽既可以进入休眠状态，也可以生长并形成分枝。许多内源性因素，如光合产物的可利用性，以及外源性因素，如养分可利用性或遮荫，都必须综合考虑以决定是否形成分枝。其潜在的调控网络很复杂，涉及植物激素和转录因子。生长素来源于茎尖，在一个称为顶端优势的过程中间接抑制芽的生长。独脚金内酯似乎通过改变生长素流来调节顶端优势。此外，转录因子BRANCHED1起着核心作用。所有这些因素的确切相互作用仍不清楚，并且存在其他模型。我们讨论了该领域的最新发现以及主要模型。植物结构在经济上具有重要意义，因为它影响作物、观赏植物以及林业或短轮伐期矮林种植树木的重要性状。因此，植物结构在植物驯化过程中已被改变。研究表明，在植物驯化和育种计划中，只有少数关键基因成为选择的目标。在此，我们基于各种实例讨论这些发现。描述了为作物管理和产量提供优势的理想株型。我们还概述了育种和生物技术方法在根据经济需求进一步改变和改善植物结构方面的潜力。
