Cadmium Toxicity In Zinnia Elegans And Identificatin Its Cadmuim-Binding Petide

• Main Author: 蔡青蒨
• Other Authors: 陳榮銳
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/81760031013346572938

碩士 === 國立臺灣大學 === 植物學研究所 === 81 === 　　Young plants of zinnia eleqans in 20-day-old or 40-day-old were cultured in nutrient solutions containing 0, 1, 5, or 10 ppm cadmium for 10 days. Cakmium toxicity were reflected on morphological changes and isozyme patterns studied with electron microscopy and electrophoreses, respectively. The accumulation of cadmium in different parts of plant was detected by a Hitachi Z-6100 atomic absorption spectroscope. Phytochelatins were purified with both ion exchange and gel filtration column-chromatographic techniques and their amino acid composition was determined by aamino acid analyzer. 　　The major morphological changes of cadmium-treated plants are the retardation of plant growth, chlorosis of leaves and shrivelling of plants. The durataion for toxicity expression is reversedly to cadmium concentration. Cadmium cause the swelling and looseness of thylakoid membrane, the increment of plastoglobuli quantity and the reduction of stack members of chroloplast grana. Besides, electron dense aggregates are often observed within cell wall, plasmalemma and vacuole of cells in vascular bundles of leaves and roots. The isozyme patterns of acid phosphatase and peroxidase are altered depending on the cadmium concentration, but those of superoxide dismutase remain uniformity. 　　The quantity of cadmium eccumulation on roots. was 4-10 fold higher than that of shoots. The older plants occupy with the higher ability of cadmium accumulation than the younger ones. The depletion of cadmium in nutrient solution maximaly reveals at the sixth day after treatment. The depletion of cadmium in successive supplement is similiar to that of discontinuous treatment. 　　Two groups of cadmium-binding peptides purified with column chromatography were identified by acidlabile sulfur test and amino acid composition. Only the smaller molecular weight fraction of cadmiumbinding peptide is phytochelatin.