Cadmium-induced changes in antioxidative systems, hydrogen peroxide content, and differentiation in Scots pine roots
Cadmium-induced changes in antioxidative systems, hydrogen peroxide content, and differentiation in Scots pine roots
复制标题
DOI：
10.1104/pp.010318
复制
发表时间：
2001-11-01
期刊：
影响因子：
7.4
通讯作者：
Polle, A
中科院分区：
文献类型：
--
作者：
Schützendübel, A;Schwanz, P;Polle, A
要调查是否镉诱导常见的植物防御途径或非特异性坏死，生理反应的时间顺序，包括过氧化氢（H2 O2）的生产，抗坏血酸-谷胱甘肽相关的抗氧化系统，次生代谢（过氧化物酶，酚类物质，木质化）的变化，和发育变化，其特征在于在水培生长的苏格兰松（樟子松）幼苗的根。镉（50妈妈，6小时）最初增加超氧化物歧化酶，抑制系统参与过氧化氢的清除（谷胱甘肽/谷胱甘肽还原酶，过氧化氢酶[CAT]，抗坏血酸过氧化物酶[APX]），并导致过氧化氢积累。根的伸长在12 h内被完全抑制。24小时后，谷胱甘肽还原酶活性恢复到对照水平; APX和CAT的刺激因子为5.5和1.5。细胞死亡增加。48 h后，非特异性过氧化物酶和木质化程度增加，APX和CAT活性下降。组织化学分析表明，可溶性酚积累在镉处理的根的细胞质中，但木质化仅限于新形成的原生木质部元素，这是发现在该地区的根尖，通常构成的伸长区。根暴露于5妈妈镉表现出不太明显的反应，只有一个小的伸长率下降。这些结果表明，在挑战镉的浓度超过解毒能力的细胞，H2 O2积累，因为氧化还原系统的不平衡。这反过来又可能触发了导致木质化的发育程序。总之，镉没有引起根尖坏死损伤，但似乎加快分化，从而导致加速老化。
To investigate whether Cd induces common plant defense pathways or unspecific necrosis, the temporal sequence of physiological reactions, including hydrogen peroxide (H2O2) production, changes in ascorbate-glutathione-related antioxidant systems, secondary metabolism (peroxidases, phenolics, and lignification), and developmental changes, was characterized in roots of hydroponically grown Scots pine (Pinus sylvestris) seedlings. Cd (50 mum, 6 h) initially increased superoxide dismutase, inhibited the systems involved in H2O2 removal (glutathione/glutathione reductase, catalase [CAT], and ascorbate peroxidase [APX]), and caused H2O2 accumulation. Elongation of the roots was completely inhibited within 12 h. After 24 h, glutathione reductase activities recovered to control levels; APX and CAT were stimulated by factors of 5.5 and 1.5. Cell death was increased. After 48 h, nonspecific peroxidases and lignification were increased, and APX and CAT activities were decreased. Histochemical analysis showed that soluble phenolics accumulated in the cytosol of Cd-treated roots but lignification was confined to newly formed protoxylem elements, which were found in the region of the root tip that normally constitutes the elongation zone. Roots exposed to 5 mum Cd showed less pronounced responses and only a small decrease in the elongation rate. These results suggest that in cells challenged by Cd at concentrations exceeding the detoxification capacity, H2O2 accumulated because of an imbalance of redox systems. This, in turn, may have triggered the developmental program leading to xylogenesis. In conclusion, Cd did not cause necrotic injury in root tips but appeared to expedite differentiation, thus leading to accelerated aging.