Submitted to: Crop Science
Publication Type: Abstract only
Publication Acceptance Date: 12/22/2003
Publication Date: 4/15/2004
Citation: Ko, T., Lee, S., Nelson, R.L., Hartman, G.L., Korban,S.S. 2004. Screening Multiple Soybean Genotypes (MG 00 TO MG VIII) for Somatic Embryogenesis Following Agrobacterium-mediated Transformation of Immature Cotyledons [abstract]. Crop Science 44: 1825-1831. Interpretive Summary: Creating transgenic soybean plants is possible but successful transformation is generally limited to a few soybean varieties. A new and more effective procedure was developed and this research was designed to test the applicability of that procedure across a wide range of varieties. We found that there was a wide range in the transformation potential among soybean varieties but 13 of 15 diverse varieties were transformed so this procedure is likely to work on all genotypes. Visual characteristics of the cultured tissue were related to transformation potential and may be used to identify varieties with good transformation potential. These results will be of interest to scientist working in the transformation of soybean.
Technical Abstract: Previously, two factors, including a vir helper strain of Agrobacterium tumefaciens (KYRT1) and an explant orientation (abaxial side oriented upward), were required for the production of high numbers of transgenic somatic embryos (SEs). In this report, 15 soybean genotypes representing maturity groups 00 to VIII were assessed for their embryogenic and transformation potentials. All genotypes were identified as embryogenic under hygromycin selection following transformation of immature cotyledons. Histochemical GUS assay of induced hygromycin-resistant SEs showed that 13 out of 15 genotypes were amenable for transformation. Wide variations among the different genotypes were observed in embryogenic capacity under hygromycin selection. Three genotypes, 'Cisne', 'Council' and 'Kunitz' were highly-embryogenic yielding more than 50% responding explants and 1.5 to 2.3 hygromycin-resistant SEs per responding explant. The transformation potential of multiple soybean genotypes was highly correlated to the embryogenic potential of immature cotyledons under hygromycin selection. It was possible to distinguish between highly- and poorly-embryogenic genotypes by visually observing the phenotype of cultured immature cotyledons. For highly-embryogenic genotypes, the induction of somatic embryos mostly originated from actively dedifferentiating and browning/necrotic tissues along the margins of the abaxial side of cultured cotyledons. Environmental factors, such as growth conditions of donor plants and/or in vitro culture conditions were also involved in observed differences among soybean genotypes/maturity groups for somatic embryogenesis/nonembryogenic callus proliferation on cultured cotyledons under selective conditions.