A Cation-Chloride Cotransporter Gene Is Required for Cell Elongation and Osmoregulation in Rice
A Cation-Chloride Cotransporter Gene Is Required for Cell Elongation and Osmoregulation in Rice
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DOI：
10.1104/pp.16.00017
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发表时间：
2016-05-01
期刊：
影响因子：
7.4
通讯作者：
Ma, Jian Feng
中科院分区：
文献类型：
--
作者：
Chen, Zhi Chang;Yamaji, Naoki;Ma, Jian Feng
水稻（Oryza sativa）的特点是具有纤维状根系；然而，根系发育的分子机制尚不完全清楚。在这里，我们分离了一个短根的水稻突变体，发现该突变体的根和芽的细胞大小比野生型水稻小。基于图谱的克隆结合全基因组测序发现，一个编码阳离子-氯共转运体（OsCCC1）的基因发生了单核苷酸突变。将OsCCC1 cDNA导入突变体后，恢复了突变体的生长，表明根和芽的生长缺陷都是由OsCCC1功能丧失引起的。生理分析表明，在所有KCl供应条件下，突变体根细胞液中的Cl-和K+浓度以及渗透压均低于野生型；然而，突变体仅在高外部Na+条件下表现出较低的Na+浓度。OsCCC1在酵母中的表达增加了K+、Na+和Cl-的积累。OsCCC1在根和芽中均有表达，但根尖表达量较高。此外，根系中的表达对Na+、K+和Cl-的供应没有响应。OsCCC1在根、叶和基节的所有细胞中均有表达。免疫印迹分析显示，OsCCC1主要定位于质膜。这些结果表明，OsCCC1通过调节离子（Cl-、K+和Na+）稳态来维持细胞渗透电位，参与细胞伸长。
Rice (Oryza sativa) is characterized by having fibrous root systems; however, the molecular mechanisms underlying the root development are not fully understood. Here, we isolated a rice mutant with short roots and found that the mutant had a decreased cell size of the roots and shoots compared with wild-type rice. Map-based cloning combined with whole-genome sequencing revealed that a single nucleotide mutation occurred in a gene, which encodes a putative cation-chloride cotransporter (OsCCC1). Introduction of OsCCC1 cDNA into the mutant rescued the mutant growth, indicating that growth defects of both the roots and shoots are caused by loss of function of OsCCC1. Physiological analysis showed that the mutant had a lower concentration of Cl- and K+ and lower osmolality in the root cell sap than the wild type at all KCl supply conditions tested; however, the mutant only showed a lower Na+ concentration at high external Na+. Expression of OsCCC1 in yeast increased accumulation of K+, Na+, and Cl-. The expression of OsCCC1 was found in both the roots and shoots, although higher expression was found in the root tips. Furthermore, the expression in the roots did not respond to different Na+, K+, and Cl- supply. OsCCC1 was expressed in all cells of the roots, leaf, and basal node. Immunoblot analysis revealed that OsCCC1 was mainly localized to the plasma membrane. These results suggest that OsCCC1 is involved in the cell elongation by regulating ion (Cl-, K+, and Na+) homeostasis to maintain cellular osmotic potential.