Somatic embryogenesis in Arachis hypogaea: revisited

Abstract

Direct somatic embryogenesis is an efficient method of plant regeneration, allowing rapid multiplication of plants in a short period. Six experiments were conducted to study the influence of auxin level on somatic embryogenesis and to optimise the concentration of auxins. Immature embryo axis was the ideal explant and 20–40 mg L^–1 of 2,4-dichlorophenoxyacetic acid was the best concentration range for obtaining the maximum number of free somatic embryos. Significant differences were observed between the genotypes for induction and the number of somatic embryos per explant. The cv. Girnar 1 produced the maximum number of somatic embryos per explant, the number of secondary somatic embryos ranging from 1.5 to 9.4. The overall germination of somatic embryos was 42.8%, and 65% of the plantlets transferred to the field survived. The development of somatic embryos was from the apical region of the embryo axes without undergoing dedifferentiation. The initial cell divided to form a tier of four cells and subsequent anticlinal and periclinal division resulted in the development of globular somatic embryos with small suspensors, followed by heart-shaped, torpedo-shaped and ‘cotyledonary’ stages.