Changes in carbohydrate content of potato calli during osmotic stress induced by mannitol.

Endogenous carbohydrate (fructose, glucose and sucrose) fractions were measured in calli of potato genotypes with different field tolerance to drought. Under in vitro stress conditions induced by 0.8 M mannitol, sucrose level of calli increased extremely in medium-tolerant (by 424.5%) and sensitive (by 302.7%) genotypes whilst the rate of increase was 12-18-times lower in the drought tolerant variety. Results suggest the applicability of sucrose as biochemical marker for distinguish drought tolerant genotypes from great population in callus culture.