Salt tolerance, salt accumulation, and ionic homeostasis in an epidermal bladder-cell-less mutant of the common ice plant Mesembryanthemum crystallinum
Salt tolerance, salt accumulation, and ionic homeostasis in an epidermal bladder-cell-less mutant of the common ice plant Mesembryanthemum crystallinum
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DOI：
10.1093/jxb/erm057
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发表时间：
2007-01-01
影响因子：
6.9
通讯作者：
Cushman, John C.
中科院分区：
文献类型：
--
作者：
Agarie, Sakae;Shimoda, Toshifumi;Cushman, John C.
普通或结晶冰植物Mesembryocarcinum stack um L.的气生表面，一种盐生兼性景天科酸代谢物种，被称为表皮囊细胞（EBC）的特化毛状体细胞覆盖。EBC被认为是作为一个外围的盐度和/或水的存储器官，以提高在高盐度或水分亏缺胁迫条件下的生存。然而，EBC对冰植物耐盐性的确切贡献仍然知之甚少。个核磁从快中子辐照诱变植物收集物中分离出缺乏EBC的Stacking um突变体。光镜和电镜观察发现，突变体植株的叶和茎的所有表面都缺乏EBC。在400 mM NaCl中生长3周后，突变体的地上部分的干重增加几乎是野生型植物的一半。与野生型植物相比，E-BC突变体还表现出降低的叶肉质化和叶和茎含水量。野生型植物的气生组织中Na+和Cl-含量比在400 mM NaCl下生长2周的突变体高约1.5倍。Na+和Cl-分配到EBC的野生型植物导致这些离子在光合活性叶组织中的浓度较低，比在面包的EBC-少突变体，特别是在高盐胁迫的条件下。钾，硝酸盐和磷酸盐离子含量下降，与注册成立的NaCl到组织中的野生型和突变体，但Na+/K+和Cl-/ NO3-含量的比例只保持在叶和茎组织的野生型植物。EBC突变体在盐胁迫下表现出显着的损害，在植物生产力的评价种子荚和种子数和平均种子重量。这些结果清楚地表明，EBC有助于肉质作为一个蓄水库和耐盐性，通过维持离子螯合和光合活性组织内的稳态。水晶
The aerial surfaces of the common or crystalline ice plant Mesembryanthemum crystallinum L., a halophytic, facultative crassulacean acid metabolism species, are covered with specialized trichome cells called epidermal bladder cells (EBCs). EBCs are thought to serve as a peripheral salinity and/or water storage organ to improve survival under high salinity or water deficit stress conditions. However, the exact contribution of EBCs to salt tolerance in the ice plant remains poorly understood. An M. crystallinum mutant lacking EBCs was isolated from plant collections mutagenized by fast neutron irradiation. Light and electron microscopy revealed that mutant plants lacked EBCs on all surfaces of leaves and stems. Dry weight gain of aerial parts of the mutant was almost half that of wild-type plants after 3 weeks of growth at 400 mM NaC1. The E-BC mutant also showed reduced leaf succulence and leaf and stem water contents compared with wild-type plants. Aerial tissues of wild-type plants had approxirnately 1.5-fold higher Na+ and Cl- content than the mutant grown under 400 mM NaCl for 2 weeks. Na+ and Cl- partitioning into EBCs of wild-type plants resulted in lower concentrations of these ions in photosynthetically active leaf tissues than in loaves of the EBC-less mutant, particularly under conditions of high salt stress. Potassium, nitrate, and phosphate ion content decreased with incorporation of NaCl into tissues in both the wild type and the mutant, but the ratios of Na+/K+ and Cl-/ NO3- content were maintained only in the leaf and stem tissues of wild-type plants. The EBC mutant showed significant impairment in plant productivity under salt stress as evaluated by seed pod and seed number and average seed weight. These results clearly show that EBCs contribute to succulence by serving as a water storage reservoir and to salt tolerance by maintaining ion sequestration and homeostasis within photosynthetically active tissues of M. crystaffinum.