Ortega Alfonso, Garrido Inmaculada, Casimiro Ilda, Espinosa Francisco
FBCMP Research Group, University of Extremadura, Campus Avenida Elvas, Badajoz, Spain.
PLoS One. 2017 Sep 5;12(9):e0183991. doi: 10.1371/journal.pone.0183991. eCollection 2017.
The alterations induced by the toxicity of antimony (Sb) in the roots and leaves of sunflower plants were determined. The plants were grown hydroponically with different concentrations of Sb, a heavy metal which reduces biomass production and growth. There was preferential accumulation of Sb in the tissues of the roots, with the concentrations in the leaves being much lower. The accumulation of other mineral elements was also altered, especially that of Fe and Zn. Chlorophyll content declined, as also did the photosynthetic efficiency, but the carotenoid content remained unaltered. The total content of phenolics, flavonoids, and phenylpropanoid glycosides rose, evidence of their participation in the defence response. Increases were observed in the amount of superoxide anion in both roots and leaves, and in lipid peroxidation levels, especially with the highest Sb concentration of 1.0 mM. The induced oxidative stress leads to a strong increase in the SOD, POX and APX antioxidant activities, while the GR activity was only increased in the leaves and at the 1.0 mM Sb concentration. In contrast, the DHAR activity increased considerably in both organs. The GSNOR activity increased only in roots, and the total RSNOs increased. The total amount of AsA + DHA increased in roots and remained unaltered in leaves, whereas that of GSH + GSSG decreased considerably in all cases. As a whole, these results are evidence for the development of a strong oxidative stress induced by Sb, with there being a clear imbalance in the content of the compounds that constitute the AsA/GSH cycle. 0.5 mM Sb enhances GST expression, especially in leaves. This, together with the increase that was observed in the amount of GSH, may play an important part in detoxification. This oxidative stress affects both the phenolic and the ROS/RNS metabolic processes, which seems to implicate their involvement in the plant's defence and response to the stress.
测定了锑（Sb）毒性对向日葵植株根和叶造成的变化。这些植株在含有不同浓度Sb的水培条件下生长，Sb是一种会降低生物量生产和生长的重金属。Sb在根组织中有优先积累，叶中的浓度则低得多。其他矿质元素的积累也发生了变化，尤其是铁和锌。叶绿素含量下降，光合效率也下降，但类胡萝卜素含量保持不变。酚类、黄酮类和苯丙素糖苷的总含量上升，证明它们参与了防御反应。根和叶中的超氧阴离子含量以及脂质过氧化水平均有所增加，尤其是在Sb浓度最高为1.0 mM时。诱导的氧化应激导致超氧化物歧化酶（SOD）、过氧化物酶（POX）和抗坏血酸过氧化物酶（APX）的抗氧化活性大幅增加，而谷胱甘肽还原酶（GR）活性仅在叶中以及1.0 mM Sb浓度下增加。相比之下，脱氢抗坏血酸还原酶（DHAR）活性在两个器官中均显著增加。亚硝基谷胱甘肽还原酶（GSNOR）活性仅在根中增加，总活性氮氧化物（RSNOs）增加。抗坏血酸（AsA）+脱氢抗坏血酸（DHA）的总量在根中增加，在叶中保持不变，而谷胱甘肽（GSH）+氧化型谷胱甘肽（GSSG）的总量在所有情况下均大幅下降。总体而言，这些结果证明了Sb诱导产生了强烈的氧化应激，构成AsA/GSH循环的化合物含量明显失衡。0.5 mM Sb会增强谷胱甘肽S-转移酶（GST）的表达，尤其是在叶中。这与观察到的GSH含量增加一起，可能在解毒过程中起重要作用。这种氧化应激影响酚类以及活性氧/活性氮（ROS/RNS）代谢过程，这似乎表明它们参与了植物对胁迫的防御和反应。
