Plant Science Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
Plant Physiol. 2013 Mar;161(3):1421-32. doi: 10.1104/pp.112.211144. Epub 2013 Jan 17.
Root architecture is a highly plastic and environmentally responsive trait that enables plants to counteract nutrient scarcities with different foraging strategies. In potassium (K) deficiency (low K), seedlings of the Arabidopsis (Arabidopsis thaliana) reference accession Columbia (Col-0) show a strong reduction of lateral root elongation. To date, it is not clear whether this is a direct consequence of the lack of K as an osmoticum or a triggered response to maintain the growth of other organs under limiting conditions. In this study, we made use of natural variation within Arabidopsis to look for novel root architectural responses to low K. A comprehensive set of 14 differentially responding root parameters were quantified in K-starved and K-replete plants. We identified a phenotypic gradient that links two extreme strategies of morphological adaptation to low K arising from a major tradeoff between main root (MR) and lateral root elongation. Accessions adopting strategy I (e.g. Col-0) maintained MR growth but compromised lateral root elongation, whereas strategy II genotypes (e.g. Catania-1) arrested MR elongation in favor of lateral branching. K resupply and histochemical staining resolved the temporal and spatial patterns of these responses. Quantitative trait locus analysis of K-dependent root architectures within a Col-0 × Catania-1 recombinant inbred line population identified several loci each of which determined a particular subset of root architectural parameters. Our results indicate the existence of genomic hubs in the coordinated control of root growth in stress conditions and provide resources to facilitate the identification of the underlying genes.
根系结构是一种高度可塑性和对环境有响应的特性，使植物能够通过不同的觅食策略来应对养分匮乏。在钾（K）缺乏（低钾）的情况下，拟南芥（Arabidopsis thaliana）参考品系哥伦比亚（Col-0）的幼苗表现出侧根伸长的强烈减少。迄今为止，尚不清楚这是缺乏 K 作为渗透调节剂的直接后果，还是为了在限制条件下维持其他器官生长而触发的响应。在本研究中，我们利用拟南芥中的自然变异来寻找对低钾的新的根系结构响应。在低钾饥饿和低钾充足的植物中，我们定量了 14 个不同的根系结构参数，这些参数构成了一个综合的根系参数集。我们发现了一个表型梯度，它将两种主要的形态适应低钾的极端策略联系起来，这两种策略源于主根（MR）和侧根伸长之间的重大权衡。采用策略 I（例如 Col-0）的品系保持 MR 生长，但牺牲了侧根伸长，而策略 II 基因型（例如 Catania-1）则为了侧枝分枝而停止 MR 伸长。K 的再供应和组织化学染色解决了这些响应的时间和空间模式。在 Col-0×Catania-1 重组自交系群体中，对 K 依赖的根系结构的数量性状位点分析确定了几个位点，每个位点都决定了特定的根系结构参数子集。我们的研究结果表明，在胁迫条件下，存在协调控制根系生长的基因组枢纽，并提供了资源来促进对潜在基因的鉴定。
