Relationship between the distribution of Cd and Zn in root tissue and the heavy metal tolerance of mulberry and Athyrium yokoscense

Abstract

The roots of mulberry and Athyrium yokoscense grown in water culture, which was mixed with Cd and Zn, were separated into 4 subcellular fractions: F1 (cell wall), F2 (cell nuclei), F3 (mitochondria and plastids) and F4 (some tiny organelles and soluble materials). These fractions were investigated for the Cd and Zn distributions. In the case of mulberry root cells, the Cd and Zn distributed in F4 were more than 30 and 40%, respectively, and in F1 about 40%. On the other hand, F1 of A. yokoscense root cells seemed to be an outstanding heavy metal accumulator, possessing Cd and Zn more than 80%. In this plant, these metals in F4 were as low as less than 10%. The tolerance of A. yokoscense for Cd and Zn was 100 times and 10 times higher, respectively, than mulberry, and this may be interpreted at least partly by the high metal-accumulation capacity of the root cell wall of this plant.