Zinc (Zn) is one of the important elements of plant growth, however, at elevated level it is toxic. Exposure of Chinese cabbage to elevated Zn2+ concentrations (5 and 10 μM ZnCl2) resulted in enhancement of total sulfur and organic sulfur concentration. Transcript level of APS reductase (APR) as a key enzyme in biosynthesis of primary sulfur compounds (cysteine and thiols), was up-regulated in both shoot and root upon exposure to elevated Zn2+, which was accompanied by an increase in the concentration of cysteine in both tissues. In contrast, the concentration of thiols increased only in the root by 5.5 and 15-fold at 5 and 10 μM Zn2+, respectively, which was in accompanied by an upregulation of ATP sulfurylase, an enzyme responsible for activation of sulfate. An elevated content of glucosinolates, mostly indolic glucosinolates, only in the shoot of plants exposed to excess level of Zn2+ coincided with an increase in gene expression of key biosynthetic enzymes and regulators (CYP79B3, CYP83B1, MYB34). Thus distinct acuumulation patterns of sulfur containing compounds in root and shoot of Chinese cabbage may be a strategy for Chinese cabbage to combat with exposure to excess Zn.

中文翻译：

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过量锌暴露后大白菜地上部和根部硫醇和硫代葡萄糖苷的差异分配

锌 (Zn) 是植物生长的重要元素之一，但是，在高水平下它是有毒的。将大白菜暴露于升高的 Zn2+ 浓度（5 和 10 μM ZnCl2）会导致总硫和有机硫浓度增加。APS 还原酶 (APR) 作为初级硫化合物（半胱氨酸和硫醇）生物合成的关键酶，在暴露于升高的 Zn2+ 后，在地上部和根中均上调，同时伴随着半胱氨酸浓度的增加在两种组织中。相比之下，在 5 μM Zn2+ 和 10 μM Zn2+ 下，硫醇的浓度仅在根中分别增加了 5.5 倍和 15 倍，同时伴随着 ATP 硫酸化酶（一种负责硫酸盐活化的酶）的上调。硫代葡萄糖苷含量升高，主要是吲哚硫代葡萄糖苷，仅在暴露于过量 Zn2+ 的植物芽中，关键生物合成酶和调节剂（CYP79B3、CYP83B1、MYB34）的基因表达增加。因此，大白菜根和芽中含硫化合物的不同积累模式可能是大白菜应对过量锌暴露的一种策略。