Menezes-Benavente Larissa, Kernodle Sheri P, Margis-Pinheiro Márcia, Scandalios John G
Laboratory for Plant Molecular Genetics, Department of Genetics, Federal University of Rio de Janeiro, Brazil.
Redox Rep. 2004;9(1):29-36. doi: 10.1179/135100004225003888.
Salinity alters general metabolic processes and enzymatic activities, causing increased production of reactive oxygen species (ROS). Expression of antioxidant defense genes would, in turn, be triggered to defend the cell against oxidative damage. We report that salt disturbed antioxidant metabolism in maize seedlings, causing detrimental effects on the growth and development of maize plantlets, increased hydrogen peroxide production and altered antioxidant activities and transcripts profiles. Excessive ROS levels were accompanied by increased catalase (CAT) activity in photosynthesizing shoots, along with induction of mRNA accumulation. Increased accumulation of superoxide dismutase (SOD) transcripts was also observed although no significant changes in total SOD enzymatic activity and isozyme profiles were detected. Higher salt concentrations (above 0.25 M NaCl) were highly detrimental to the plants, causing arrested growth and severe wilting, among other effects. Histochemical detection of H(2)O(2) by 3,3-diaminobenzidine (DAB) staining indicated a collapse of the leaf veins, with hydrogen peroxide leaking to neighboring cells. In agreement to these observations, Sod1, Sod2, Sod4, Sod4A, as well as all Cat transcripts were severely inhibited in plants exposed to high salt concentrations.
盐度会改变一般代谢过程和酶活性，导致活性氧（ROS）的产生增加。反过来，抗氧化防御基因的表达会被触发，以保护细胞免受氧化损伤。我们报告称，盐干扰了玉米幼苗的抗氧化代谢，对玉米幼苗的生长发育产生了有害影响，增加了过氧化氢的产生，并改变了抗氧化活性和转录本谱。过量的ROS水平伴随着光合茎中过氧化氢酶（CAT）活性的增加以及mRNA积累的诱导。尽管未检测到超氧化物歧化酶（SOD）总酶活性和同工酶谱的显著变化，但也观察到SOD转录本的积累增加。较高的盐浓度（高于0.25 M NaCl）对植物极为有害，导致生长停滞和严重萎蔫等影响。通过3,3 - 二氨基联苯胺（DAB）染色对H₂O₂进行组织化学检测表明叶脉崩溃，过氧化氢泄漏到相邻细胞中。与这些观察结果一致，在暴露于高盐浓度的植物中，Sod1、Sod2、Sod4、Sod4A以及所有Cat转录本均受到严重抑制。
