Improved cotyledonary node method using an alternative explant derived from mature seed for efficient Agrobacterium-mediated soybean transformation
The utility of transformation for soybean improvement requires an efficient system for production of stable transgenic lines. We describe here an improved cotyledonary node method using an alternative explant for Agrobacterium tumefaciens-mediated soybean transformation. We use the term “half-seed” to refer to this alternative cotyledonary explant that is derived from mature seed of soybean following an overnight imbibition and to distinguish it from cotyledonary node derived from 5–7-day-old seedlings. Transformation efficiencies using half-seed explants ranged between 1.4 and 8.7% with an overall efficiency of 3.8% based on the number of transformed events that have been confirmed in the T1 generation by phenotypic assay using the herbicide Liberty® (active ingredient glufosinate) and by Southern analysis. This efficiency is 1.5-fold higher than the cotyledonary node method used in our laboratory. Significantly, the half-seed system is simple and does not require deliberate wounding of explants, which is a critical and technically demanding step in the cotyledonary node method.
KeywordsAgrobacterium tumefaciens Cotyledonary node Glufosinate Half-seed Soybean Transformation
The authors thank Joanna Harbaugh, Amanda Ehrler and Francois Torney for their technical assistance; Mike Webber, Bayer CropScience, USA for graciously giving us Liberty® herbicide; and Bronwyn Frame and John Pesek for critical review of the manuscript and valuable suggestions. This work was partially supported by the Iowa Soybean Promotion Board and the North Central Soybean Research Program.
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