After a one-step selection procedure with glyphosate added to the callus medium, tobacco regenerants were obtained from calluses surviving on field doses of the herbicide. The lipid and sterol compositions of potted plants from the two original cultivars which underwent the selection procedure but without glyphosate, and the selected regenerants were investigated. Controls were derived from micropropagation and not from seeds. They served as appropriate controls for comparison with glyphosate regenerants, i.e. they underwent exactly the same experimental conditions except for the glyphosate treatment.
Plant regeneration was strongly (at one-step selection) or fully (at stepwise selection) inhibited. Only a few glyphosate-tolerant plants (seven of Neurokop AZ4 and five of Zlatna arda) were obtained which were cloned and potted. At least 10 plants of one clone per genotype were used for the further biochemical analyses.
The spraying of the tobacco plants from the cultivars with glyphosate led to a decrease of monogalactosyl diacylglycerol content and increase of the saturated fatty acids in all glycolipid classes. The concentration of stigmasterol increased and that of sitosterol decreased only in Zl.arda variety.
In the regenerants there were different changes in lipid composition, concerning mainly a decrease of monogalactosyl diacylglycerols (MGDG) and an increase of digalactosyl diacylglycerols (DGDG) in ZLarda-derived regenerants and increase of the amounts of neutral lipids and decrease of phospholipids (PL) in the Neurokop A,,-derived regenerants. Surprisingly, after treatment of the regenerants with glyphosate, the MGDG amounts in these regenerants were higher than in the controls, which could mean a lesser ability to control ion permeability.