SEEKING IMPROVED NUTRITIONAL PROPERTIES FOR THE POTATO - ETHIONINE-RESISTANT PROTOCLONES

Russet Burbank leaf protoplasts were cultured in Shepard's (1980) cell layer (CL) medium containing the amino acid analog ethionine (ETN), a t concentrations ranging from 0 to 6 mu M. Repeated counts of viable c ells and dividing colonies during the 21 day incubation period permitt ed calculation of plating efficiencies for each ETN concentration. Pla ting efficiency was observed to decrease when ETN concentration in CL exceeded 3 mu M. Calli which developed were placed on Shepard's (1980) C media containing ETN concentrations up to 200 mu M; however, few ca lli survived concentrations above 100 mu M. Regenerated plants were gr own to maturity and resulting tubers were analyzed for free methionine content. Selected protoclones produced tubers with free methionine co ntent as much as 2.66 times that of the Russet Burbank control.