Figure 3.

Schematic of a transfer cell inductive system using Vicia faba cotyledons. An equatorial view of a V. faba seed sliced transversely in half. A maternal seed coat encloses two large cotyledons. At the maternal/filial interface, thin-walled parenchyma cells of the seed coat and abaxial epidermal cells of the cotyledons (solid dark green lines) trans-differentiate to a transfer cell morphology. In contrast, adaxial epidermal cells of the cotyledons do not trans-differentiate to a transfer cell morphology. Upon surgical removal of cotyledons from their enclosing seed coats and transfer to a MS medium, cotyledon adaxial epidermal cells undergo a synchronous trans-differentiation to transfer cells that are structurally and functionally identical to their abaxial counterparts. Sister cotyledons of each seed are randomly allocated to MS medium alone or a MS medium carrying a pharmacological agent that interferes with developmental signals or wall building machinery.