Development of a Superficial Meristem During Somatic Embryogenesis from Immature Cotyledons of Soybean (Glycine max L.)

Initial events were studied in the development of an embryogenic meristem during somatic embryogenesis from in vitro cultured immature cotyledons of soybean. The presence of 2,4-D in the culture medium led to the formation of a superficial embryogenic tissue associated with the abaxial epidermis of 3 mm cotyledons. Additionally, 2,4-D initiated rapid non-morphogenic periclinal division in the parenchyma tissues of the cotyledon. Consequent internal expansion disrupted and eventually ruptured the apparently quiescent adaxial epidermis. The profound difference in the in vitro response between abaxial and adaxial epidermes is discussed in relation to their relative roles in nutrient transport during seed development in vivo.