| Summary: | 碩士 === 國立臺灣大學 === 植物學研究所 === 83 === The aim of this study is to investigate the changes of morphology, composition of plasma membrane and physiological processes of plants in response to heavy metal stress.
Five-week-old and/or six-week-old plants of Zinnia elegans were grown in culture medium containing 5ppm Cd(NO3)2, 5ppm Cd(NO3)2 after 1ppm Cd(NO3)2 pretreatment for 1 week or 12.5ppm CuSO4.
The symptoms of cadmiun toxicity were plant shortening, leaf chlorosis and inhibition of root growth. Root was especially sensitive to excess copper. The response was associated with retarded growth. Copper toxicity caused concomitantly internode shortening and old leaf chlorosis.
Plasma membrane vesicles of leaf were isolated and purificated
by 6.0 ﹪ two-phase partition system. Plasma membrane purity was
examined in according to the sensitivity of ATPases to various
inhibitors. The major fatty acids of plasma membrane were
palmitic acid(16:0), linoleic acid (18:2) and linolenic acid
(18:3). The ratio of unsaturated fatty acids to saturated fatty
acids were reduced in plants that were treated with cadmium or
copper. The contents of phospholipid were increased with
increasing duration of copper treatment, but the contents of
glycolipid were decreased.
Cadmium lowered the protein contents of leaf tissues. Cadmiunalso caused the reduction of chlorophyll contents and total amount of carotenoids. Moreover, lipid peroxides were obviously higher in the presence of copper. Plants pretreated with low concentration of cadmiun were induced to produce more nonprotein thiol-containing compounds. The isozymes pattern and enzyme activity of superoxide dismutase, peroxidase and acid
phosphatase were altered by various application me thods and the
durations of cadmiun or copper treatment.
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