title: Overexpression of bacterial γ-glutamylcysteine synthetase mediates changes in cadmium influx, allocation and detoxification in poplar.
abstract: Overexpression of bacterial γ-glutamylcysteine synthetase in the cytosol of Populus tremula × P. alba produces higher glutathione (GSH) concentrations in leaves, thereby indicating the potential for cadmium (Cd) phytoremediation. However, the net Cd(2+) influx in association with H(+) /Ca(2+) , Cd tolerance, and the underlying molecular and physiological mechanisms are uncharacterized in these poplars. We assessed net Cd(2+) influx, Cd tolerance and the transcriptional regulation of several genes involved in Cd(2+) transport and detoxification in wild-type and transgenic poplars. Poplars exhibited highest net Cd(2+) influxes into roots at pH 5.5 and 0.1 mM Ca(2+) . Transgenics had higher Cd(2+) uptake rates and elevated transcript levels of several genes involved in Cd(2+) transport and detoxification compared with wild-type poplars. Transgenics exhibited greater Cd accumulation in the aerial parts than wild-type plants in response to Cd(2+) exposure. Moreover, transgenic poplars had lower concentrations of O2 ˙(-) and H2 O2 ; higher concentrations of total thiols, GSH and oxidized GSH in roots and/or leaves; and stimulated foliar GSH reductase activity compared with wild-type plants. These results indicate that transgenics are more tolerant of 100 μM Cd(2+) than wild-type plants, probably due to the GSH-mediated induction of the transcription of genes involved in Cd(2+) transport and detoxification.
authors.affiliation: College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China; Department of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China.
authors.forename: Jiali
authors.initials: J
authors.lastname: He
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Ma
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhang
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Heinz
authors.initials: H
authors.lastname: Rennenberg
authors.forename: Xingqi
authors.initials: X
authors.lastname: Cheng
authors.forename: Zhi-Bin
authors.initials: ZB
authors.lastname: Luo
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000235:genetics; D004151:Dipeptides / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006859:Hydrogen / Q000378:metabolism; D008658:Inactivation, Metabolic; D008954:Models, Biological; D024301:Plant Bark / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D025341:Principal Component Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014934:Wood / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004151:Dipeptides; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D002104:Cadmium; D013481:Superoxides; D006859:Hydrogen; C017341:gamma-glutamylcysteine; D002118:Calcium
keywords: Populus; antioxidant; cadmium (Cd); glutathione; ion flux; oxidative stress; phytoremediation; plasma membrane H+-ATPase