Ma Jing, Lv Chunfang, Xu Minli, Chen Guoxiang, Lv Chuangen, Gao Zhiping
Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China.
Institute of Food and Crops, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing, 210014, China.
Environ Sci Pollut Res Int. 2016 Jan;23(2):1768-78. doi: 10.1007/s11356-015-5439-x. Epub 2015 Sep 23.
The present study was conducted to examine the effects of increasing concentrations of chromium (Cr(6+)) (0, 25, 50, 100, and 200 μmol) on rice (Oryza sativa L.) morphological traits, photosynthesis performance, and the activities of antioxidative enzymes. In addition, the ultrastructure of chloroplasts in the leaves of hydroponically cultivated rice (O. sativa L.) seedlings was analyzed. Plant fresh and dry weights, height, root length, and photosynthetic pigments were decreased by Cr-induced toxicity (200 μM), and the growth of rice seedlings was starkly inhibited compared with that of the control. In addition, the decreased maximum quantum yield of primary photochemistry (Fv/Fm) might be ascribed to the decreased the number of active photosystem II reaction centers. These results were confirmed by inhibited photophosphorylation, reduced ATP content and its coupling factor Ca(2+)-ATPase, and decreased Mg(2+)-ATPase activities. Furthermore, overtly increased activities of antioxidative enzymes were observed under Cr(6+) toxicity. Malondialdehyde and the generation rates of superoxide (O2̄) also increased with Cr(6+) concentration, while hydrogen peroxide content first increased at a low Cr(6+) concentration of 25 μM and then decreased. Moreover, transmission electron microscopy showed that Cr(6+) exposure resulted in significant chloroplast damage. Taken together, these findings indicate that high Cr(6+)concentrations stimulate the production of toxic reactive oxygen species and promote lipid peroxidation in plants, causing severe damage to cell membranes, degradation of photosynthetic pigments, and inhibition of photosynthesis.
本研究旨在考察不同浓度（0、25、50、100和200 μmol）的铬（Cr(6+)）对水稻（Oryza sativa L.）形态特征、光合作用性能及抗氧化酶活性的影响。此外，还分析了水培水稻（O. sativa L.）幼苗叶片叶绿体的超微结构。Cr诱导的毒性（200 μM）降低了植株鲜重、干重、株高、根长及光合色素含量，与对照相比，水稻幼苗生长受到明显抑制。此外，初级光化学最大量子产率（Fv/Fm）的降低可能归因于活性光系统II反应中心数量的减少。光合磷酸化受抑制、ATP含量及其偶联因子Ca(2+)-ATPase降低以及Mg(2+)-ATPase活性下降证实了这些结果。此外，在Cr(6+)毒性作用下，抗氧化酶活性明显增加。丙二醛和超氧阴离子（O2̄）生成率也随Cr(6+)浓度增加而升高，而过氧化氢含量在25 μM的低Cr(6+)浓度下先升高，然后降低。此外，透射电子显微镜显示，Cr(6+)暴露导致叶绿体显著损伤。综上所述，这些发现表明高浓度的Cr(6+)刺激植物中有毒活性氧的产生并促进脂质过氧化，对细胞膜造成严重损伤，光合色素降解并抑制光合作用。
