Soybean (Glycine max) transformation using mature cotyledonary node explants.

Agrobacterium tumefaciens-mediated transformation of soybeans has been steadily improved since its development in 1988. Soybean transformation is now possible in a range of genotypes from different maturity groups using different explants as sources of regenerable cells, various selectable marker genes and selective agents, and different A. tumefaciens strains. The cotyledonary-node method has been extensively investigated and across a number of laboratories yields on average greater than 1% transformation efficiency (one Southern-positive, independent event per 100 cotyledonary-node explants). Continued improvements in the cotyledonary-node method concomitant with further increases in transformation efficiency will enhance broader adoption of this already productive transformation method for use in crop improvement and functional genomics research efforts.