Effect of Carbohydrates on Somatic Embryogenesis in Subcultured Nucellar Callus of Citrus Cultivars

Abstract

Summary The effect of several carbohydrates — sucrose, galactose, lactose, glucose and fructose — at 8 to 256 mM, on growth and embryogenesis of nucellar calli from five Citrus cultivars, was studied. While galactose and lactose over a broad concentration range enhanced embryogenesis in all calli studied, sucrose supported embryogenesis only at the lower levels tested (8–32 mM with various calli). Glucose and fructose were least effective in stimulating embryogenesis. Galactose and even more so lactose were also very effective in enhancing development of large embryos. All the sugars except fructose supported good callus growth over the concentration range tested. Addition of IAA, kinetin or GA3 to galactose, especially above 32 mM sugar, resulted in varying degrees of inhibition of embryogenesis. After 10 weeks in culture, compared with 5 weeks, the inhibition caused by IAA diminished significantly.