Uncontrolled uptake of Na+ is the reason that many species are sensitive to salinity. Suberin is a protective barrier found in the walls of root endodermal cells that appears to be important for salt tolerance, yet its specific protective mechanism has not been fully elucidated. Here we investigated the role of aliphatic suberin in protecting plants against salt stress by using a mutant of Arabidopsis, cyp86a1, which exhibits a significant reduction of root aliphatic suberin. We found that NaCl significantly increased suberization in roots of hydroponic-grown wild-type plants, but not in cyp86a1. Cyp86a1 exhibited a salt-sensitive phenotype. Compared with wild-type, Na+ accumulation in shoots was higher in cyp86a1. We provide evidence that increased Na+ uptake was via the root transcellular pathway. Furthermore, cyp86a1 accumulated less K+ in shoots than wild-type under NaCl stress, which was a consequence of increased K+ efflux from the root vasculature. Additionally, we provide evidence that aliphatic suberin reduces inflow of water across the root endodermis under non-stress conditions but reduces the backflow of water to the medium under salt stress. Finally, we propose a model for the role of aliphatic suberin in restricting Na+ influx, K+ efflux and water backflow in plants under saline conditions.

中文翻译：

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脂肪族木栓素通过限制 Na+ 流入、K+ 流出和水回流赋予拟南芥耐盐性

不受控制地摄取 Na+ 是许多物种对盐度敏感的原因。Suberin 是一种在根内胚层细胞壁中发现的保护屏障，似乎对耐盐性很重要，但其具体的保护机制尚未完全阐明。在这里，我们通过使用拟南芥的突变体 cyp86a1 研究了脂肪族木栓素在保护植物免受盐胁迫方面的作用，该突变体表现出根脂肪族木栓素的显着减少。我们发现 NaCl 显着增加了水培生长的野生型植物根部的木栓化，但在 cyp86a1 中没有。Cyp86a1 表现出盐敏感表型。与野生型相比，cyp86a1 的芽中 Na+ 积累更高。我们提供的证据表明增加的 Na+ 吸收是通过根跨细胞途径。此外，在 NaCl 胁迫下，cyp86a1 在枝条中积累的 K+ 比野生型少，这是根脉管系统 K+ 流出增加的结果。此外，我们提供的证据表明，脂肪族木栓质在非胁迫条件下减少了穿过根内皮层的水流入，但在盐胁迫下减少了水回流到培养基中。最后，我们提出了一个关于脂肪族木栓质在盐分条件下限制植物中 Na+ 流入、K+ 流出和水回流的作用模型。