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Root Morphology and Zn 2+ Uptake Kinetics of the Zn Hyperaccumulator of Sedum alfredii Hance
Author(s) -
LI TingQiang,
YANG XiaoE,
HE ZhenLi,
YANG JinYan
Publication year - 2005
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/j.1744-7909.2005.00117.x
Subject(s) - ecotype , hyperaccumulator , chemistry , kinetics , botany , morphology (biology) , biology , phytoremediation , environmental chemistry , heavy metals , physics , genetics , quantum mechanics
Root morphology and Zn 2+ uptake kinetics of the hyperaccumulating ecotype (HE) and non‐hyperaccumulating ecotype (NHE) of Sedum alfredii Hance were investigated using hydroponic methods and the radiotracer flux technique. The results indicate that root length, root surface area, and root volume of NHE decreased significantly with increasing Zn 2+ concentration in growth media, whereas the root growth of HE was not adversely affected, and was even promoted, by 500 μmol/L Zn 2+ . The concentrations of Zn 2+ in both ecotypes of S. alfredii were positively correlated with root length, root surface area and root volumes, but no such correlation was found for root diameter. The uptake kinetics for 65 Zn 2+ in roots of both ecotypes of S. alfredii were characterized by a rapid linear phase during the first 6 h and a slower linear phase during the subsequent period of investigation. The concentration‐dependent uptake kinetics of the two ecotypes of S. alfredii could be characterized by the Michaelis‐Menten equation, with the V max for 65 Zn 2+ influx being threefold greater in HE compared with NHE, indicating that enhanced absorption into the root was one of the mechanisms involved in Zn hyperaccumulation. A significantly larger V max value suggested that there was a higher density of Zn transporters per unit membrane area in HE roots. (Managing editor: Ping HE)