Improved regeneration system in locally developed yellow and white maize inbred lines (Zea mays L.)
2007
Guittap, E.J.M. | Refuerzo, L.C. | Damasco, O.P., Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Plant Breeding Crop Science Cluster)
Establishment of an effective and reliable protocol for regeneration is a prerequisite for genetic transformation of maize. Two white (P53 and WL-07) and two yellow (Pi17 and Pi23) inbred lines developed at the Institute of Plant Breeding, University of the Philippines at Los Banos, were selected as sources of explants for the optimization of maize regeneration. In the attempt to increase embryogenic callus initiation in immature embryos, the standard medium developed by CIMMYT was modified using different levels of Dicamba (1-2 mg/L)and 2,4-D (1-4 mg/L). Embryogenic and friable calli were obtained from both Dicamba and 2,4-D supplemented media. Further proliferation of embryogenic calli (dark condition), differentiation of shoots and shoot-like structure (partial light), and the plantlet regeneration were then obtained from all lines tested. Single and multiple shoots were regenerated from embryogenic calli. Single shoots regenerants showed complete plant parts and exhibited typical growth very similar to a germinating embryo. In comparison multiple shoots were either leafy regenerants without distinct growing points or a clamp of shoots. Addition of liquid MS medium with different levels if indole acetic acid (IAA) and napthalene acetic acid (NAA) significantly imrproved rooting of the regenerants. Plantlets with 2 to 4 leaves and robust root system acclimatized for a week in the greenhouse (temperature approximately 30 deg C) were successfully established in the field.
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