Salt-induced inhibition of phosphorus transport in lettuce plants

Copper interferes with numerous physiological processes and can be toxic at low concentrations. We examined the effect of a 2-week exposure to various concentrations of copper on the structure of the nucleus in maize root meristem cells by transmission electron microscopy. Copper uptake and distribution in the plants, as well as DNA synthesis were also investigated. Treatment with Cu induced alterations in the structure of the nucleus, resulting mainly in a greater density of chromatin. Morphometric analysis showed that the part of the condensed chromatin in the nucleus might be increased by Cu, an observation that was correlated with decreased DNA synthesis as measured by incorporation of ³H-thymidine. Copper may therefore play a role in chromatin structure and one of the manifestations of Cu toxicity is an alteration in the structure of the nucleus, leading to decreased DNA synthesis.