Methods to increase the starch content of potato tuber callus tissue

Attempts were made to increase the starch content of callus tissue from tubers of cvs Lemhi Russet and Russet Burbank by varying growth regulator concentration, sugar source, sugar concentration, temperature and callus shape. Starch content was always higher in media containing no growth regulators. Callus spread over the media contained more starch than unbroken rectangular or cube-shaped callus. Sucrose was superior to glucose and fructose for starch formation. A sucrose concentration of 20 % produced more starch than lower concentrations. Callus growth decreased as the sucrose concentration increased. ‘Lemhi Russet’ callus incubated with 8 % sucrose at 20, 25 and 30 °C contained 1.2, 0.4 and 0.8 % starch respectively, which was much higher than in ‘Russet Burbank’ callus. With varying amounts of mannitol as an osmoticum in 8 % sucrose, the most starch was found in the medium containing 5 % mannitol.