Carbohydrate nutrition and anthocyanin accumulation in light grown and etiolated shoot cultures of carob (Ceratonia siliqua L.)

Abstract

Production of anthocyanins was studied in shoot cultures of carob at high (45.9 μmol s-1m-2) and low (9.2 μmol s-1m-2) irradiance levels and in darkness in relation to carbohydrate nutrition. Anthocyanin production was stimulated by light, but it also occurred in etiolated shoot cultures which developed in darkness. Anthocyanins were present in both leaves and shoot tips. The major factor affecting anthocyanin production was carbohydrate nutrition, with sucrose as a choice superior to fructose and glucose. The carbohydrate effect was clearly osmotic in nature, since anthocyanin production increased even at supraoptimal concentrations detrimental to the growth of shoot cultures. This conclusion was further confirmed in experiments in which sucrose was partly replaced with the sugar alcohols sorbitol and mannitol.

Keywords

• carbohydrate nutrition
• anthocyanin accumulation
• light-grown and etiolated shoot cultures
• Ceratonia siliqua