Barrier function of the cell wall during uptake of nickel ionsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Cell walls were isolated from roots of six plant species to study their ion-exchange capacity for nickel ions (S (Ni)) at Ni(2+) concentration of 10(-3) M. The S (Ni) values varied depending on the plant species from 50 to 150 mu mol Ni(2+) per gram dry wt; the sorption capacity increased in a row: Poaceae < Chenopodiaceae < Fabaceae. At pH 5 the sorption capacity of cell walls for nickel ions was determined by the presence of carboxyl groups of polygalacturonic acid in the polymeric cell-wall matrix. In all cases the ion-exchange capacity of cell walls was higher at pH 8 than at pH 5, indicating that Ni(2+) binds also to a carboxyl group different from that of polygalacturonic acid. Irrespective of plant species, the presence of EDTA in the solution diminished drastically the absorption capacity of cell walls for Ni(2+). It is concluded that the presence of 10(-3) M EDTA weakens the defense properties of cell walls. The sequestration of Ni(2+) in the cell wall can be considered as an effective means of plant cell defense against elevated concentrations of nickel ions in the external medium.