Cadmium accumulation and distribution in populations of Phytolacca americana L. and the role of transpiration.
The concentrations of heavy metals in Phytolacca americana L. and corresponding soil samples from three contaminated sites and an uncontaminated site were studied. Hydroponic experiments were also conducted to investigate the Cd uptake ability and mechanism of P. americana. The field results showed that the average Cd concentration was 42 mg kg(-1) in P. americana leaves, with the highest concentration of 402 mg kg(-1) found at Datianwan. A significant relationship was observed between the concentrations of Cd in leaves and those of corresponding soils on a logarithmic scale. Under laboratory hydroponic conditions, the maximum Cd concentration in aerial tissues of P. americana was 637 mg kg(-1), under treatment with 100 microM Cd. The population from the uncontaminated site (Zijinshan) also had a remarkable ability to accumulate Cd in shoots to concentrations well in excess of 100 microM in the hydroponic experiment, similar to the population from contaminated site, suggesting that Cd accumulation is a constitutive trait of P. americana. In the presence of 100 microM Cd, the addition of polyethylene glycol decreased leaf transpiration, the shoot Cd concentration, and the shoot/root Cd concentration ratio. There was a significantly positive relationship between the shoot Cd concentration and the leaf transpiration of P. americana. A similar significant positive correlation was also obtained between the shoot/root Cd concentration and leaf transpiration. Moreover, pretreatment with 5 microM abscisic acid or 5 microM HgCl(2) significantly decreased the Cd concentration in P. americana shoots. These results suggest that transpiration has an important role in Cd accumulation in shoots of P. americana.
Liu
Xiaoqing
X
College of Life Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China.
Peng
Kejian
K
Wang
Aiguo
A
Lian
Chunlan
C
Shen
Zhenguo
Z
D000040:Abscisic Acid / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000032:analysis*; D010788:Photosynthesis / Q000187:drug effects; D029604:Phytolacca americana / Q000737:chemistry* / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D018520:Plant Shoots / Q000737:chemistry; D018526:Plant Transpiration / Q000187:drug effects; D011092:Polyethylene Glycols / Q000494:pharmacology; D012989:Soil Pollutants / Q000032:analysis*
D010937:Plant Growth Regulators; D012989:Soil Pollutants; D002104:Cadmium; D011092:Polyethylene Glycols; D000040:Abscisic Acid