Xylogenesis and lignification in plant tissue cultures differently affected by 8-hydroxyquinoline sulphate

Summary An established callus tissue derived from mesophyll cells ofSedum telephium L. was used to assess the influence of 8-hydroxyquinoline sulphate (Quinosol) on the differentiation of tracheary cells.Electron microscopic study of cells from calli grown in the presence of Quinosol (20.55 and 41.10 M) showed no marked ultrastructural differences compared to controls at the same developmental stages. Growth of calli diminished with increasing concentrations of Quinosol, being drastically affected by the maximum dose used (82.20 M). On the other hand, xylogenesis, expressed as the number of tracheary elements to parenchyma cells, increased with increasing concentrations of the drug. However, lignin and phenolic content responded differently, increasing at a low Quinosol dose (20.55 M) but decreasing at higher concentrations of the drug (41.10 and 82.20 M).The impaired growth of the culture was due to decreased cell proliferation in spite of an increase in differentiation of xylem-like cells. However, the calli with numerous tracheary elements synthesized less lignin than calli with a lower percentage of such cells.