Méndez Andrea A E, Pena Liliana B, Benavides María P, Gallego Susana M
Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Junín 956, Buenos Aires, C1113AA, Argentina; IQUIFIB-CONICET, Argentina.
Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Junín 956, Buenos Aires, C1113AA, Argentina; IQUIFIB-CONICET, Argentina.
Biochimie. 2016 Dec;131:128-136. doi: 10.1016/j.biochi.2016.09.021. Epub 2016 Oct 8.
In the present study we evaluated the pre-treatment (priming) of Arabidopsis thaliana plants with sodium nitroprusside (SNP), a NO-donor, as an interesting approach for improving plant tolerance to cadmium stress. We focused on the cell redox balance and on the methionine sulfoxide reductases (MSR) family as a key component of such response. MSR catalyse the reversible oxidation of MetSO residues back to Met. Five MSRA genes and nine MSRB genes have been identified in A. thaliana, coding for proteins with different subcellular locations. After treating 20 days-old A. thaliana (Col 0) plants with 100 μM CdCl, increased protein carbonylation in leaf tissue, lower chlorophyll content and higher levels of reactive oxygen species (ROS) in chloroplasts were detected, together with increased accumulation of all MSR transcripts evaluated. Further analysis showed reduction in guaiacol peroxidase activity (GPX) and increased catalase (CAT) activity, with no effect on ascorbate peroxidase (APX) activity. Pre-exposition of plants to 100 μM SNP before cadmium treatment restored redox balance; this seems to be linked to a better performance of antioxidant defenses. Our results indicate that NO priming may be acting as a modulator of plant antioxidant system by interfering in oxidative responses and by preventing up-regulation of MSR genes caused by metal exposure.
在本研究中，我们评估了用硝普钠（SNP，一种一氧化氮供体）对拟南芥植物进行预处理（引发），这是一种提高植物对镉胁迫耐受性的有趣方法。我们关注细胞氧化还原平衡以及甲硫氨酸亚砜还原酶（MSR）家族，将其作为这种反应的关键组成部分。MSR催化甲硫氨酸亚砜（MetSO）残基可逆地氧化回甲硫氨酸（Met）。在拟南芥中已鉴定出五个MSRA基因和九个MSRB基因，它们编码具有不同亚细胞定位的蛋白质。用100μM CdCl处理20日龄的拟南芥（Col 0）植物后，检测到叶片组织中蛋白质羰基化增加、叶绿素含量降低以及叶绿体中活性氧（ROS）水平升高，同时所评估的所有MSR转录本的积累也增加。进一步分析表明，愈创木酚过氧化物酶（GPX）活性降低，过氧化氢酶（CAT）活性增加，而抗坏血酸过氧化物酶（APX）活性没有受到影响。在镉处理前将植物预先暴露于100μM SNP可恢复氧化还原平衡；这似乎与抗氧化防御的更好表现有关。我们的结果表明，一氧化氮引发可能通过干扰氧化反应以及防止金属暴露引起的MSR基因上调，从而作为植物抗氧化系统的调节剂。
