Ecophysical and ultrastructural effects of copper in Thlaspi ochroleucum (Cruciferae)

Abstract

The toxic effects of Cu on growth, element uptake, chlorophyll content, cellular ultrastructure, and morphometry of a Zn-and Pb-tolerant ecotype of Thlaspi ochroleucum have been investigated in hydroponic cultures. Increasing Cu concentrations in nutrient solutions caused a reduction of root growth, a decrease in total chlorophyll content in the leaves, an increased uptake of Cu, and a decreased uptake of nutrient elements such as Ca, Mg, K, and Fe. Gross anatomy and intercellular spaces of leaves of plants treated with Cu did not differ significantly from the controls. However, cells contained fewer and smaller chloroplasts that lacked starch grains and contained a number of large plastoglobuli. The volume fraction of the internal membrane system was reduced, but ultrastructurally it was similar to the control. These findings, in combination with the reduced quantity of chlorophyll, indicate that the existence of a well-organized internal membrane system does not necessarily imply the presence of high amounts of chlorophyll. Other leaf cell components, such as mitochondria, microbodies, and nuclei, displayed little ultrastructural malformation. In roots, however, all cell types were so disorganized by treatment with Cu that cell organelles could hardly be identified. Our results indicate that toxic effects of Cu appear to be manifested primarily in roots and secondarily on aerial plant parts. Key words: chlorophyll content, copper, element uptake, morphometric cytology, ultrastructure, Thlaspi ochroleucum.

Copper-stress induced alterations in protein profile and antioxidant enzymes activities in the in vitro grown Withania somnifera L.

“…It is well-known that Cu 2+ is required by biological systems as a catalytic enzyme component but excess amount of Cu causes physiological responses that can decrease plant growth and develop toxic symptoms (Salt et al 1998;Ouzounidou et al 1992). Higher concentration of Cu can induce the formation of harmful ROS, leading to lipid peroxidation.…”

Field study of the effects of excess copper on wheat photosynthesis and productivity

“…In chloroplasts it can alter the architecture of the thylakoid membranes which in turn affects some light reaction processes especially those associated with PSII (Baszynski et a!. 1988;Eleftheriou and Karataglis 1989;Ouzounidou et a!. 1992).…”

“…Distilled water was added to obtain a constant volume. Copper-content was determined using a Perkin Elmer 2380 atomic absorption spectrometer (Ouzounidou et al 1992). The Cu-content was determined in the leaves where gas exchange measurements were carried out.…”

“…However, in excessive quantities Cu becomes toxic as it interferes with photosynthetic and respiratory processes, protein synthesis and development of plant organelles (Wainwright and W oolhouse 1977;Sandmann and Boger 1980;Baszynski et al 1982;Ouzounidou et al 1992Ouzounidou et al , 1993Agarwala et al 1995).…”

Copper effect on the protein composition of photosystem II

“…It was shown in vivo that the decrease of the photochemical activity caused by Cu(II) was accompanied by an alteration of the structure and composition of the thylakoid membranes, which can influence the conformation and function of the photosystems (Baszynski et al 1988, Ouzounidou et al 1992, Lidon et al 1993). Baszynski and Krupa (1995) …”