A novel role for the root cap in phosphate uptake and homeostasis.
A novel role for the root cap in phosphate uptake and homeostasis.
复制标题
DOI：
10.7554/elife.14577
复制
发表时间：
2016-04-06
期刊：
影响因子：
7.7
通讯作者：
Nussaume L
中科院分区：
文献类型：
--
作者：
Kanno S;Arrighi JF;Chiarenza S;Bayle V;Berthomé R;Péret B;Javot H;Delannoy E;Marin E;Nakanishi TM;Thibaud MC;Nussaume L
根冠在感知环境信号以及通过改变分生组织活性来调节根生长方面发挥着重要作用。尽管根冠在控制根部发育过程中发挥着明确的作用，但其在营养方面的功能仍然不清楚。在这里，我们使用反式激活策略和创新的高分辨率实时 33P 成像技术，通过拟南芥中的靶向细胞失活或磷酸盐转运互补，揭示了其在磷酸盐营养中的作用。值得注意的是，根-土壤交换表面的根冠细胞尺寸较小，占幼苗总磷吸收量的很大一部分（约 20%）。这种 Pi 吸收水平足以产生芽生物量（在土壤中最多增加 180%），并抑制 Pi 饥饿诱导的基因。这些结果扩展了我们对这一重要组织的理解，从之前描述的环境感知作用扩展到矿物质营养和稳态控制中的新功能。 DOI：http://dx.doi.org/10.7554/eLife.14577.001 所有植物都需要磷酸盐才能生长，因为它是 DNA 和许多其他生物分子的主要成分。地球上的大部分土壤都缺乏磷酸盐，因此农田通常需要补充肥料，为农作物提供这种必需的养分。然而，磷肥正变得稀缺，预计在不久的将来其质量将会下降。因此，植物生物学家必须确定如何使植物适应这种资源的有限供应，以便为不断增长的世界人口维持高作物产量。众所周知，植物通过位于构成根外层的细胞中的特定蛋白质转运蛋白吸收磷酸盐。这些蛋白质高度集中在根尖，虽然这种特殊组织以感知重力和光而闻名，但尚未证明它在磷酸盐吸收中发挥作用。菅野，Arrighi 等人。现在已经使用转基因拟南芥植物证明磷酸盐可以通过根尖周围的小细胞吸收。实验表明，吸收的磷酸盐在几分钟内迅速到达叶子，帮助植物生长并改变其新陈代谢。由于根尖可以积累大量的磷酸盐以维持其自身的活性，因此区分从环境中吸收磷酸盐和植物内已有的磷酸盐的重新分配非常重要。菅野，Arrighi 等人。通过开发新的放射性显微成像技术解决了这个问题。磷酸盐转运蛋白也存在于根内的细胞层内，但其目的和活性尚未得到很好的描述。需要进一步的研究来分析其他根细胞层在磷酸盐吸收和运输中的作用，新开发的技术将有助于破译所涉及的机制。 DOI：http://dx.doi.org/10.7554/eLife.14577.002
The root cap has a fundamental role in sensing environmental cues as well as regulating root growth via altered meristem activity. Despite this well-established role in the control of developmental processes in roots, the root cap’s function in nutrition remains obscure. Here, we uncover its role in phosphate nutrition by targeted cellular inactivation or phosphate transport complementation in Arabidopsis, using a transactivation strategy with an innovative high-resolution real-time 33P imaging technique. Remarkably, the diminutive size of the root cap cells at the root-to-soil exchange surface accounts for a significant amount of the total seedling phosphate uptake (approximately 20%). This level of Pi absorption is sufficient for shoot biomass production (up to a 180% gain in soil), as well as repression of Pi starvation-induced genes. These results extend our understanding of this important tissue from its previously described roles in environmental perception to novel functions in mineral nutrition and homeostasis control. DOI: http://dx.doi.org/10.7554/eLife.14577.001 All plants need phosphate to grow because it is a major component of DNA and many other biological molecules. Most of the Earth’s soil is poor in phosphate, and so farmland is routinely supplemented with fertilizers to provide crops with this essential nutrient. However, phosphate fertilizers are becoming scarce and their quality is expected to decline in the near future. Plant biologists must therefore determine how to adapt plants to a restricted supply of this resource, in order to sustain high crop yields for the growing world population. Plants are known to absorb phosphate through specific protein-based transporters located in the cells that make up the outer layer of roots. These proteins are highly concentrated at the root tip, and while this specialized tissue is well-known for perceiving gravity and light, it had not been shown to play a role in phosphate absorption. Kanno, Arrighi et al. have now used genetically modified Arabidopsis plants to demonstrate that phosphate can be taken up via the small cells that surround the root tip. The experiments showed that the absorbed phosphate rapidly reaches the leaves within minutes, helps the plant grow and modifies its metabolism. As the root tip can accumulate high amounts of phosphate in order to sustain its own activity, it was important to distinguish uptake of phosphate from the environment from redistribution of phosphate already within the plant. Kanno, Arrighi et al. tackled this issue through the development of a new radioactive micro-imaging technique. Phosphate transporters are also present within the cell layers within the root, but their purpose and activity are not well described. Further studies are needed to analyze the role of other root cell layers in phosphate uptake and transport, and the newly developed techniques will help decipher the mechanisms involved. DOI: http://dx.doi.org/10.7554/eLife.14577.002