CALLUS-TISSUE OF SOLANUM-TUBEROSUM L CULTURED IN THE PRESENCE OF THE PYRETHROID DELTAMETHRIN

The effect of Decis (deltamethrin as active ingredient) on callus tiss ue of Solanum tuberosum L. cv. Desiree was studied. Decis is an agroch emical currently used on field grown potato plants to control the Colo rado beetle, a potato pest. Deltamethrin added to the culture medium i nterferes with the behaviour of callus tissue. After 5 h of culture, t he level of total proteins was higher in treated tissue than in the co ntrol, 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. T his similarity between control and treated tissues, after 14 days of c ulture, occurred as a result of the treatment with deltamethrin which caused a decrease of soluble proteins, but an increase in insoluble pr oteins whereas the opposite was observed for control callus. SDS-PAGE of both soluble and insoluble proteins showed that only quantitative d issimilarities occurred. This longer treatment also increased the chlo rophyll content. Ultrastructural study of the cells revealed that tiss ue callus cultured for 14 days in the presence of deltamethrin had pla stids containing a more developed membranous system, with a higher num ber of grana and with more compartments than in control cells. Deltame thrin also promoted the abundance of vesicles associated with dictyoso mes.This response of the callus tissue to Decis added to the callus me dium parallels the behaviour of potato plants treated with this agroch emical under field conditions (Fidalgo, Santos & Salema, 1993).