Factors affecting soybean cotyledonary node transformation

Cotyledonary node transformation efficiency was evaluated using a sonicatio n assisted Agrobacterium-mediated transformation (SAAT) protocol, three dis similar A. tumefaciens strains, and explants derived from 28 diverse cultiv ars and/or genotypes of soybean [Glycine max (L.) Merr.]. The explants were evaluated at 10 and 45 days after co-cultivation for transformation with a binary vector containing both a GUS-intron gene and an NPTII selectable ma rker. The best overall strain of A. tumefaciens was determined to be KYRT1 based on stable GUS transformation of soybean cotyledonary node explants me asured at the terminal 45 day evaluation point. SAAT did not increase stabl e transformation at 45 days post co-cultivation. SAAT was determined to sig nificantly decrease shoot proliferation of some genotypes, but it is unclea r what effect this may have on the recovery of transformed shoots. Signific ant differences were also detected between genotypes for transformation and shoot proliferation frequency.