Callus tissue of Solanum tuberosum L. cultured in the presence of the pyrethroid deltamethrin

The effect of Decis (deltamethrin as active ingredient) on callus tissue of Solanum tuberosum L. cv. Désirée was studied. Decis is an agrochemical currently used on field grown potato plants to control the Colorado beetle, a potato pest. Deltamethrin added to the culture medium interferes with the behaviour of callus tissue. After 5 h of culture, the level of total proteins was higher in treated tissue than in the control, and SDS-PAGE showed that deltamethrin promoted the increase of some soluble proteins. After 24 h and 14 days of culture, the level of total proteins became similar in both treated and control material. This similarity between control and treated tissues, after 14 days of culture, occurred as a result of the treatment with deltamethrin which caused a decrease of soluble proteins, but an increase in insoluble proteins whereas the opposite was observed for control callus. SDS-PAGE of both soluble and insoluble proteins showed that only quantitative dissimilarities occurred. This longer treatment also increased the chlorophyll content. Ultrastructural study of the cells revealed that tissue callus cultured for 14 days in the presence of deltamethrin had plastids containing a more developed membranous system, with a higher number of grana and with more compartments than in control cells. Deltamethrin also promoted the abundance of vesicles associated with dictyosomes. This response of the callus tissue to Decis added to the callus medium parallels the behaviour of potato plants treated with this agrochemical under field conditions (Fidalgo, Santos & Salema, 1993).