title: Photosynthesis performance, antioxidant enzymes, and ultrastructural analyses of rice seedlings under chromium stress.
abstract: 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.
authors.affiliation: Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.affiliation: Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China.
authors.forename: Chunfang
authors.initials: C
authors.lastname: Lv
authors.affiliation: Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China.
authors.forename: Minli
authors.initials: M
authors.lastname: Xu
authors.affiliation: Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China.
authors.forename: Guoxiang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Institute of Food and Crops, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing, 210014, China.
authors.forename: Chuangen
authors.initials: C
authors.lastname: Lv
authors.affiliation: Jiangsu Key Lab of Biodiversity and Biotechnology, School of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210023, Jiangsu, China. majingjing319@163.com.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Gao
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002857:Chromium / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D018384:Oxidative Stress; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D002857:Chromium; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D002374:Catalase
keywords: Chromium stress; Photosynthesis; Rice; Ultrastructure