The Effect of Polymetallic Pollution on Ion-Exchange Properties of Barley Root and Shoot Cell Walls.

For the first time we determined the ion-exchange properties of the cell walls (CWs) isolated from roots and shoots of barley plants grown in the conditions of polymetallic pollution. The content of all the types of cation-exchange groups in the CWs was found to be considerably higher in the shoots than in the roots, which resulted in higher metal-binding capacity of the shoot CWs and higher swelling capacity of CW polymers. It was shown for the first time that the heavy metal excess causes an increase in the content of demethylated pectins in the shoot CWs.

Features of ionogenic group composition in polymeric matrix of lily pollen wall.

The composition of ionogenic groups and ion-exchange capacity were studied in the polymeric matrix of cell walls isolated from the pollen grain and tissues of vegetative organs (leaves and stems) of Lilium longiflorum Thunb. The ion-exchange capacity was evaluated at different pH values and ionic strength of 100 mM. In the two-layered pollen wall and the somatic cell walls four types of ionogenic groups were found: amino groups, two carboxyl groups (represented by residues of uronic and hydroxycinnamic acids), and phenolic OH-groups. The groups of all four types are present in the intine, whereas the exine contains one type of anion-exchange and two types of cation-exchange groups. The contents of each type group and their ionization constants were determined. The qualitative and quantitative compositions of structural polymers of the pollen intine and somatic cell walls are significantly different. It is suggested that hydroxycinnamic acids should be involved in cross-linking of polysaccharide chains in both the intine and somatic cell primary walls, and such cross-links play a crucial role in the structural organization and integrity of the pollen grain wall.