Increased glutathione biosynthesis plays a role in nickel tolerance in Thlaspi nickel hyperaccumulators
Increased glutathione biosynthesis plays a role in nickel tolerance in Thlaspi nickel hyperaccumulators
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DOI：
10.1105/tpc.104.023036
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发表时间：
2004-08-01
期刊：
影响因子：
11.6
通讯作者：
Salt, DE
中科院分区：
文献类型：
--
作者：
Freeman, JL;Persans, MW;Salt, DE
目前已知世界上有400多种植物在其茎部超积累各种微量金属（Cd、Co、Cu、Mn、Ni和Zn）、类金属（As）和非金属[Se]。其中，近四分之一是芸苔科成员，包括许多高富集镍达其茎干重3%的苔属植物。我们观察到，茎部组织中谷胱甘肽、半胱氨酸和o -乙酰- l-丝氨酸（OAS）的浓度与从蛇形土壤中收集的各种高积累体（包括Thlaspi goesingense、T. oxyceras和T. rosulare）以及非积累体亲缘体（包括T. perfoliatum、T. arvense和拟南芥）的Ni超积累能力密切相关。对奥地利镍超积累体T. goesingense的进一步分析表明，在这种超积累体中观察到高浓度的OAS、Cys和GSH，与丝氨酸乙酰转移酶（SAT）和谷胱甘肽还原酶的组成性高活性相一致。SAT催化L-Ser的乙酰化生成OAS， OAS既是硫同化的关键正调节因子，也是Cys生物合成的碳骨架。Cys和GSH代谢的这些变化也与T. goesingense超积累Ni和抵抗其破坏性氧化作用的能力相一致。在非富集植物拟南芥中，发现T. goesingense SAT的过量生产导致OAS、Cys和谷胱甘肽的积累，模拟了在Ni超富集植物中观察到的生化变化。在这些转基因拟南芥中，谷胱甘肽浓度与对Ni诱导的生长抑制和氧化应激的抗性增强密切相关。综上所述，这些证据支持了我们的结论，即由组成性的SAT活性升高驱动的GSH浓度升高，参与赋予Thlaspi Ni超积累细胞对Ni诱导的氧化应激的耐受性。
Worldwide more than 400 plant species are now known that hyperaccumulate various trace metals (Cd, Co, Cu, Mn, Ni, and Zn), metalloids (As) and nonmetals [Se) in their shoots. Of these, almost one-quarter are Brassicaceae family members, including numerous Thlaspi species that hyperaccumulate Ni up to 3% of there shoot dry weight. We observed that concentrations of glutathione, Cys, and O-acetyl-L-serine (OAS), in shoot tissue, are strongly correlated with the ability to hyperaccumulate Ni in various Thlaspi hyperaccumulators collected from serpentine soils, including Thlaspi goesingense, T. oxyceras, and T. rosulare, and nonaccumulator relatives, including T. perfoliatum, T. arvense, and Arabidopsis thaliana. Further analysis of the Austrian Ni hyperaccumulator T. goesingense revealed that the high concentrations of OAS, Cys, and GSH observed in this hyperaccumulator coincide with constitutively high activity of both serine acetyltransferase (SAT) and glutathione reductase. SAT catalyzes the acetylation Of L-Ser to produce OAS, which acts as both a key positive regulator of sulfur assimilation and forms the carbon skeleton for Cys biosynthesis. These changes in Cys and GSH metabolism also coincide with the ability of T. goesingense to both hyperaccumulate Ni and resist its damaging oxidative effects. Overproduction of T. goesingense SAT in the nonaccumulator Brassicaceae family member Arabidopsis was found to cause accumulation of OAS, Cys, and glutathione, mimicking the biochemical changes observed in the Ni hyperaccumulators. In these transgenic Arabidopsis, glutathione concentrations strongly correlate with increased resistance to both the growth inhibitory and oxidative stress induced effects of Ni. Taken together, such evidence supports our conclusion that elevated GSH concentrations, driven by constitutively elevated SAT activity, are involved in conferring tolerance to Ni-induced oxidative stress in Thlaspi Ni hyperaccumulators.