High Frequency Plant Regeneration via Somatic Embryogenesis in Cell Suspension Cultures of Cowpea, Vigna unguiculata (L.) Walp

Embryogenic callus was induced from primary leaves of Vigna unguiculata (L.) Walp. in MS medium (Murashige and Skoog, 1962) containing 2,4-dichlorophenoxyacetic acid (2,4-D). Greenish-white, friable embryogenic calluses were used to establish suspension cultures. A shaking speed of 90 rpm and 0.4 ml packed cell volume per 25 ml medium were found to be optimal for maintaining suspension cultures. Globular, heart-shaped and torpedo-shaped embryos were developed in suspension culture containing 4.52 µM 2,4-D. Maturation of cotyledonary-stage somatic embryos was achieved on 0.05 µM 2,4-D, 5 µM abscisic acid and 3% mannitol. Twenty-two percent of the embryos were converted into plants and survived; survival in the field was 8-10%.