CADMIUM UPTAKE AND ACCUMULATION, SUBCELLULAR DISTRIBUTION AND CHEMICAL FORMS IN YOUNG SEEDLINGS OF SALIX BABYLONICA L.

To understand the cadmium (Cd) accumulative ability and resistance mechanism of Cd stress by Salix babylonica L., Cd uptake and accumulation, subcellular distribution and chemical forms were investigated in S. babylonica exposed to 10, 50 and 100 mu M Cd for 7 and 14 d. Subcellular localization of Cd on the surface of leaves and mature zone of root tips was investigated by SEM and EDXA. The results indicated that the seedling growth was accelerated by 10 mu M Cd, and significantly inhibited by 50 and 100 mu M Cd. Root was the main organ to uptake and accumulate Cd, and the contents of Fe and Mn decreased significantly. The order that distributions of Cd among tissue fractions was: cell wall > soluble fraction > cell organelle. The proportion of CdNaCl was the highest, Cd integrated with pectates and proteins in cell walls may be responsible for the adaptation of S. babylonica to Cd stress. The results of EDXA indicated that root cell wall play a key role in Cd detoxicity and the vascular bundle have more potential in Cd transportation. The Cd content of leaf main vein was higher than leaf epidermal cells.