背景回顾：The formation of Casparian strips (CS) and the deposition of suberin at the endodermis of plant roots are thought to limit the apoplastic transport of water and ions. 

主要研究：We investigated the specific role of each of these apoplastic barriers in the control of hydro-mineral transport by roots and the consequences on shoot growth.

研究方法：A collection of Arabidopsis thaliana mutants defective in suberin deposition and/or CS development was characterized under standard conditions using a hydroponic system and the Phenopsis platform. 

结果1-木栓质：Mutants altered in suberin deposition had enhanced root hydraulic conductivity, indicating a restrictive role for this compound in water transport. 

结果2-凯氏带：In contrast, defective CS directly increased solute leakage and indirectly reduced root hydraulic conductivity. Defective CS also led to a reduction in rosette growth, which was partly dependent on the hydro-mineral status of the plant. 

结果3-木栓质与凯氏带：Ectopic suberin was shown to partially compensate for defective CS phenotypes.

结论：Altogether, our work shows that the functionality of the root apoplastic diffusion barriers greatly influences the plant physiology, and that their integrity is tightly surveyed.

 摘 要 

植物根组织中内皮层上凯氏带的形成和木栓质的沉积被认为是水和离子质外体运输的限制条件。作者研究了每一种质外体屏障在控制根系水溶矿物营养运输中的具体作用，以及对地上部生长的影响。使用水培系统和Phenopsis表型分析平台，作者对标准条件下的一组在木栓质沉积和/或凯氏带发育方面存在缺陷的拟南芥突变体进行了鉴定。木栓质沉积存在缺陷的突变体，其根系的导水率得到了提升，表明根中木栓质的沉积对于水分运输是起限制作用的。相反，凯氏带发育存在缺陷的突变体，其溶质渗漏加剧，并且间接降低了根系的导水率。凯氏带发育缺陷还导致了莲座生长减少，而这部分取决于植物的水溶矿物营养的状态。异位的木栓质能够部分补偿凯氏带发育缺陷的表型。综上，本文的研究结果表明，根组织质外体扩散屏障的功能极大地影响了植物生理。