COMPETENCE FOR REGENERATION OF CUCUMBER COTYLEDONS IS RESTRICTED TO SPECIFIC DEVELOPMENTAL STAGES

The total duration of the plant regeneration process from cucumber (Cucumis sativus L.) cotyledonary explants was only six weeks, which included the induction of buds and their development into plants. Regeneration of shoots from cotyledons from three to five day-old seedlings ranged up to 100%. The regenerated plants were morphologically normal, flowered and set seed. The regeneration capacity of cotyledons from seven days-old and older seedlings was lowered dramatically. Most of those regenerated plants were polyploid/mixoploid and had an abnormal morphology. During seedling development (3 to 13 days), the DNA content of cotyledonary cells changed from 2C to 4C and more. The results show that the decrease in regeneration competence correspond with the change in DNA content of the cotyledonary cells.