Changes in photosynthetic apparatus of mustard (<Emphasis Type="Italic">Sinapis alba</Emphasis>) cotyledons following cycloheximide and kinetin treatments

Biochemical and accompanying structural characteristics of the photosynthetic process were studied in mustard seedlings cultivated on medium with increasing concentrations of cycloheximide alone as well as in combination with various kinetin concentrations. After 7 days of cultivation the contents of total chlorophyll, carotenoids and content of Rubisco in mustard cotyledons were determined. The content of chlorophyll pigments and carotenoids decreased in dependence of cycloheximide concentration. Following antibiotic treatment the content of both Rubisco subunits markedly decreased. In addition cycloheximide caused disturbance in mesophyll organization and chloroplast ultrastructure. Kinetin applied with cycloheximide increased the amount of photosynthetic pigments as well as of Rubisco, compared to the cycloheximide alone. In the seedlings treated with cycloheximide+kinetin the structure of leaf mesophyll and chloroplast membrane system was similar to control. Our results indicate that kinetin diminished the negative effects of cycloheximide on photosynthetic pigments and Rubisco as well as on the structural traits of the cotyledons.