Starch-enhanced synthesis and release of amylolytic enzymes from normal and crown gall tumor tobacco tissue culture cells

Abstract

The response of tobacco crown gall tumor cells growing in tissue culture to a substitution of starch for sucrose as the carbon source in the medium was compared with the response of normal tobacco tissue culture cells. In both cases amylolytic activity was secreted into the medium. The increase in extracellular amylolytic activity was preceded by an increase in intracellular activity. The increase in intracellular amylolytic enzymes was sensitive to cycloheximide and to actinomycin D indicating that enzyme induction at the level of mRNA synthesis was required. No significant difference between the responses of normal and tumor cells was observed. Thus crown gall tumor cells were as capable as normal cells of sensing and responding to an alteration in the carbon source in the external medium.