SOMATIC EMBRYOGENESIS AND PLANT REGENERATION FROM IMMATURE EMBRYO INDUCED CALLUS OF MAIZE (ZEA MAYS L.)

Somatic embryogenesis is the process by which somatic cells, under induction conditions, generate embryogenic cells, which go through a series of morphological and biochemical changes that result in the formation of a somatic embryo. These characteristics have designated somatic embryogenesis into a model system for the study of morphological, physiological, molecular and biochemical events occurring during the onset and development of embryogenesis in higher plants. In our experiments somatic embryogenesis and plant regeneration was achieved from immature embryos of two maize (Zea mays L.) lines A18 and A19. Callus was initiated on N6 medium supplemented with 1 mg.dm(-3) 2,4-D, N6 salts, 2 % sucrose, 25 mmol.dm(-3) proline, 100 mg.dm(-3) casein hydrolysate, N6 vitamins, 10 mg.dm(-3) silver nitrate, 3g gelrite. Induction of primary callus ranged between 0 and 93%. Generally, three types of callus were formed: embryogenic, non-embryogenic and organogenic callus. Embryogenic callus was formed within two weeks of culture in callus maintenance medium. Induction of embryogenic callus ranged between 0 and 5%. Somatic embryos were matured on N6 medium supplemented with 6% sucrose and 1 mg.dm(-3) NAA. After transfer of embryogenic calli on regeneration medium containing MS medium supplemented with 2% sucrose, somatic embryos started to form plantlets. Callus initiation and plant regeneration were genotype dependent. Regenerated plants were transferred on the surface of solidified MS medium supplemented with myo-inositol.