C. Cabasson et al., CHARACTERISTICS OF CITRUS CELL-CULTURES DURING UNDIFFERENTIATED GROWTH ON SUCROSE AND SOMATIC EMBRYOGENESIS ON GALACTOSE, Physiologia Plantarum, 93(3), 1995, pp. 464-470
Growth of willow-leaf mandarin (Citrus deliciosa Ten.) nucellar callus
cultures without embryo formation was supported on sucrose as the sol
e carbon source. Somatic embryogenesis was obtained by substituting ga
lactose for sucrose at the same concentration (0.15 M). A histocytolog
ical study revealed proliferation of young globular embryos during the
first half of the 18-day culture cycle, irrespective of the carbon so
urce. However, during the second half of the cycle, further embryo dev
elopment failed in cell cultures on sucrose-containing medium. The rat
e of cell growth and the carbohydrate depletion of the medium were 3-f
old higher on sucrose than on galactose-containing medium. Cell suspen
sions on sucrose differed by an increase in calcium, phosphorus, magne
sium and potassium utilization soon after subculturing, followed by a
sharp decrease. Finally, the phosphorus utilization rate per g dry wei
ght formed was 2-fold higher in cell cultures on galactose during the
second half of the culture cycle, coinciding with further embryo ontog
enesis.