title: Cadmium tolerance of carbon assimilation enzymes and chloroplast in Zn/Cd hyperaccumulator Picris divaricata.
abstract: To better understand the photosynthesis under stress, the effect of cadmium on carbon assimilation and chloroplast ultrastructure of a newly found Zn/Cd hyperaccumulator Picris divaricata in China was investigated in solution culture. The shoot and root Cd concentrations increased with increase in Cd supply, reaching maxima of 1109 and 5604mgkg(-1) dry weight at 75microM Cd, respectively. As Cd supply to P. divaricata increased, the shoot and root dry weight, leaf water content (except 75microM Cd), concentrations of chlorophyll a and b, chlorophyll a/b ratio and the concentration of carotenoids were not depressed at high Cd. However, the stomatal conductance, transpiration rate, net photosynthetic rate and intercellular CO(2) concentration were significantly affected when the Cd concentration reached 10, 10, 25 and 75microM, respectively. Meanwhile, carbonic anhydrase (CA; EC 4.2.1.1) activity and Rubisco (EC 4.1.1.39) content reached maxima in the presence of 50 and 5microM Cd, respectively. In addition, CA activity correlated positively with shoot Cd in plants treated with Cd at a range of 0-50microM. Moreover, the activities of NADP(+)-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13), Rubisco and fructose-1, 6-bisphosphatase (EC 3.1.3.11) were not significantly suppressed by increased Cd supply. Although the mesophyll cell size was reduced, chloroplast ultrastructure remained intact at the highest Cd treatment. Our finding revealed that P. divaricata chloroplast and the enzymes of carbon assimilation tolerate high levels of Cd, demonstrating its potential in possible application in phytoremediation.
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, PR China.
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Ying
authors.forename: Rong-Liang
authors.initials: RL
authors.lastname: Qiu
authors.forename: Ye-Tao
authors.initials: YT
authors.lastname: Tang
authors.forename: Peng-Jie
authors.initials: PJ
authors.lastname: Hu
authors.forename: Hao
authors.initials: H
authors.lastname: Qiu
authors.forename: Hong-Ru
authors.initials: HR
authors.lastname: Chen
authors.forename: Tai-Hong
authors.initials: TH
authors.lastname: Shi
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Morel
mesh_terms: D019659:Asteraceae / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity*; D002256:Carbonic Anhydrases / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation; D010788:Photosynthesis / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D002104:Cadmium; D002734:Chlorophyll; D002338:Carotenoids; D012273:Ribulose-Bisphosphate Carboxylase; D002256:Carbonic Anhydrases; D015032:Zinc