This study was initiated to test the embryogenic potential of immature cotyledons (3-5 mm long) of Texas bluebonnet (Lupinus texensis). The embryo initiation medium consisted of B5 salts and vitamins with 3% sucrose and 22.6 μM 2,4-D alone or in combination with 1-15 μM of various cytokinins. Within 15-20 days, globular embryos were formed on the distal end of the cotyledons. Eventually the entire cotyledon surface was covered by embryo-like structures. Addition of cytokinins to the medium did not increase the percentage of cultures which formed embryos. In fact, addition of thidiazuron severely inhibited embryogenesis. Following transfer to an embryo maturation medium (MS medium with 0.38 μM abscisic acid alone or in combination with benzyladenine or zeatin) for 10-14 days, the embryos were placed in MS medium supplemented with GA (2.9 μM) or glutamine (200 mg/liter) with or without activated charcoal (0.5%) for embryo germination and plantlet development. Most of the embryos exhibited precocious germination and well-developed roots but failed to produce normal shoots. Therefore, additional work is needed to improve embryo conversion frequency.
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