A Rice Mutant Sensitive to Al Toxicity is Defective in the Specification of Root Outer Cell Layers
A Rice Mutant Sensitive to Al Toxicity is Defective in the Specification of Root Outer Cell Layers
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DOI：
10.1093/pcp/pcp050
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发表时间：
2009-05-01
影响因子：
4.9
通讯作者：
Ma, Jian Feng
中科院分区：
文献类型：
--
作者：
Huang, Chao-Feng;Yamaji, Naoki;Ma, Jian Feng
水稻根系的外细胞层由表皮、外表皮和厚壁组织组成，具有保护根系免受土壤胁迫的作用。在这里，我们报道了一个突变体，其外细胞层的规格有缺陷，并研究了这些层在铝和其他金属抗性中的作用。形态学和组织化学观察表明，基于Al敏感性分离的突变体在靠近根尖分生组织的表皮层中经常出现不规则的周周细胞分裂模式。突变体的侧根帽难以从表皮上剥离，表皮细胞变小、不规则，根毛明显减少。此外，一些外表皮细胞转化为额外的厚壁组织细胞。然而，野生型和突变体之间的内细胞层数没有差异。该突变体的根系生长与野生型水稻相似，但Al对其根系伸长的抑制作用更大。Morin染色显示Al渗入突变体皮质内细胞。此外，突变体对镉和镧等金属也很敏感。综上所述，我们的研究结果表明，根外细胞层通过阻止金属渗透到内细胞中来保护根免受铝和其他金属的毒性。遗传分析表明，突变体表型受位于水稻2号染色体短臂上的单隐性基因控制。
Outer cell layers of rice roots, which comprise epidermis, exodermis and sclerenchyma, have been proposed to protect the roots from various stresses in soil. Here, we report a mutant which is defective in the specification of outer cell layers, and examined the role of these layers in Al and other metal resistance. Morphological and histochemical observations revealed that the mutant isolated based on Al sensitivity frequently showed a disordered pattern of periclinal cell division in the epidermal layers at a region close to the root apical meristem. The lateral root caps in the mutant became difficult to peel off from the epidermis, and epidermal cells became smaller and irregular with far fewer root hairs. Furthermore, some exodermal cells were transformed into additional sclerenchyma cells. However, there was no difference in the inner cell layers between the wild-type rice and the mutant. The mutant showed similar root growth to the wild-type rice in the absence of Al, but greater inhibition of root elongation by Al was found in the mutant. Morin staining showed that Al penetrated into the inner cortical cells in the mutant. Furthermore, the mutant was also sensitive to other metals including Cd and La. Taken together, our results indicate that root outer cell layers protect the roots against the toxicity of Al and other metals by preventing metal penetration into the inner cells. Genetic analysis showed that the mutant phenotypes were controlled by a single recessive gene, which was located on the short arm of rice chromosome 2.