Cellular compartmentation of zinc in leaves of the hyperaccumulator Thlaspi caerulescens
Cellular compartmentation of zinc in leaves of the hyperaccumulator Thlaspi caerulescens
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DOI：
10.1104/pp.119.1.305
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发表时间：
1999-01-01
期刊：
影响因子：
7.4
通讯作者：
McGrath, SP
中科院分区：
文献类型：
--
作者：
Küpper, H;Zhao, FJ;McGrath, SP
采用能量色散x射线微量分析和单细胞汁液提取技术研究了锌在超蓄积体海苔（Thlaspi caulescens）叶片中的细胞区隔。对冷冻、水化后的叶片组织进行能量色散x射线微分析，结果表明，与叶肉细胞相比，表皮锌积累量显著增加。幼叶和成熟叶表皮细胞的相对锌浓度与细胞长度呈线性相关，表明表皮细胞的空泡化可能促进锌的优先积累。单细胞液取样结果表明，在茎干重为2万μ g Zn（-1）的植物中，表皮液泡液中锌含量是叶肉液的5 ~ 6.5倍，平均达到385 mM。即使在不增加锌含量的培养基中，表皮液泡中仍有明显的锌优先积累现象。表皮汁液中K、Cl、P、Ca的浓度普遍随Zn的增加而降低。目前的研究表明，锌主要以可溶性形式被隔离在T. caerulescens叶片的表皮液泡中，而叶肉细胞能够耐受汁液中至少60 mM的锌。
Cellular compartmentation of Zn in the leaves of the hyperaccumulator Thlaspi caerulescens was investigated using energy-dispersive x-ray microanalysis and single-cell sap extraction. Energy-dispersive x-ray microanalysis of frozen, hydrated leaf tissues showed greatly enhanced Zn accumulation in the epidermis compared with the mesophyll cells. The relative Zn concentration in the epidermal cells correlated linearly with cell length in both young and mature leaves, suggesting that vacuolation of epidermal cells may promote the preferential Zn accumulation. The results from single-cell sap sampling showed that the Zn concentrations in the epidermal vacuolar sap were 5 to 6.5 times higher than those in the mesophyll sap and reached an average of 385 mM in plants with 20,000 mu g Zn g(-1) dry weight of shoots. Even when the growth medium contained no elevated Zn, preferential Zn accumulation in the epidermal vacuoles was still evident. The concentrations of K, Cl, P, and Ca in the epidermal sap generally decreased with increasing Zn. There was no evidence of association of Zn with either P or S. The present study demonstrates that Zn is sequestered in a soluble form predominantly in the epidermal vacuoles in T. caerulescens leaves and that mesophyll cells are able to tolerate up to at least 60 mM Zn in their sap.