Schematic workflow of the callus starch models system. The scheme presents the essential steps. (a) Immature embryo transformation. (b) Callus containing both transgenic and non-trangenic parts. Transgenic parts are identified by GFP, excised and sub-cultured (c) Fully transgenic callus is obtained. (d) Callus cultures maintenance with subculturing steps every three weeks. Sampling and starch analysis. (e) Transgenic plants can be regenerated.