EXPRESSION OF ALPHA-AMYLASE IN CULTURED CALLUS OF FRENCH BEAN

alpha-Amylase (EC 3.2.1.1) expression was found in calli of French bea n (Phaseolus vulgaris L. cv Goldstar). We examined enzyme activity in the calli to investigate influence of gibberellin and sugars on enzyme expression. After subculture of the calli, alpha-amylase activity dec reased, and then increased at a stationary phase of callus growth. Exo genous application of gibberellin and an inhibitor of gibberellin synt hesis, uniconazole, did not have any significant effects on the enzyme expression, Sugar starvation increased the activity, while addition o f metabolizable sugars, such as sucrose, glucose and maltose, to the m edium repressed expression, Addition of 6% mannitol, a non-metabolizab le sugar, to the medium induced higher alpha-amylase expression as com pared to addition of 3% mannitol, This result suggests that osmotic st ress enhances alpha-amylase activity in the calli, Furthermore, high c oncentrations of agar in the medium increased alpha-amylase activity i n the calli, It is probable that high concentrations of agar prevented incorporation of nutrient into the calli and induced the alpha-amylas e activity in the calli.