Cyto-histological features of malformations in mulberry roots induced by heavy metals

1984 The Journal of Sericultural Science of Japan  
Anatomical studies on the effects of heavy metals on the morp"logenesis of mulberry roots were carried out, using malformed roots induced by heavy metals. Cadmium-induced imbalances in the growth of root tissue were observed, especially inhibition of cell division in the cortex, shrinkage of stelar cells by extraordinary expansion of cortical cells, cell crushing and malformations of the nuclei. Copper mainly induced histogenetic disorders of the root apex, chimeralization of the tissues,
more » ... nce of cell growth within and between tissues, separation of the tissues from each other and condensation of nuclear matter by collapse of the membrane system. Zinc affected scarcely root morphogenesis and induced only local swelling of the cortex. In soils containing excess heavy metals such as zinc and cadmium in area arround zinc smelters, growth of mulberry has been observed to be inhibited and various malformed roots have appeared (Homma and Shirata, 1977). Similar growth inhibition and malformation of roots were induced experimentally by supplying heavy metals (Takagishi et al., 1976). As roots make contact with soils containing excess heavy metals which have been accumulating for a long time in mulberry fields, the most important and primary problems to consider on the effects of heavy metals on mulberry plants must be how they influence the function and morphogenesis of roots. However, few studies have been performed on the mechanism of growth inhibition by heavy metals from the point of view of the effects on mulberry morphogenesis. This experiment has therefore concentrated on the effects of heavy metals on the morphogenesis of mulberry roots, and anatomical research into malformations induced by heavy metals was carried out. Materials and Methods Mulberry seeds of the variety "Roso" were sown on 0.8% agar containing Knop's medium and grown for 15 days after germination at 28-Mulberry seedlings were then cultured for a week in Kasugai's nutrient solutions for land crops with and without heavy metals. Two cm long root segments were collected from tips and :.fixed in FAA. Segments were dehydrated, embedded in paraffin and sections 8sections were then stained using the PAS reactions and observed under a light microscope. Additional heavy metals such as cadmium, copper and zinc were used as sulfate salts at concentrations of 10.5 M to 10.3 M and the pH of each nutrient solution was adjusted to within 6.4 to 6.6. Results Cyto-histological features of tissues from near -191-
doi:10.11416/kontyushigen1930.53.191 fatcat:nxhtsgh2mfachnrlof7366ip7e