Genotype screening for proliferative embryogenesis and biolistic transformation of short-season soybean genotypes.

Eighteen of 20 short-season soybean (Glycine max (L.) Merrill) genotypes (maturity group 0 and 00) screened for proliferative embryogenic capacity formed secondary globular embryos, at rates of 1-70% of cultured immature cotyledons. Five genotypes produced embryogenic cultures which were proliferative for at least 6 months. Proliferative embryogenic cultures of AC Colibri and X2650-7-2-3 were bombarded using a Bio-Rad PDS-1000/He particle gun. Co-bombardments with plasmid pairs pHygr (encoding a type IV aminoglycoside phosphotransferase;aphIV) and pRD300pat (encoding a phosphinothricin N-acetyltransferase;pat) or pRD300pat and pFF19G (β-glucuronidase;uidA or gus) resulted, respectively, in 12 hygromycin-selected lines with multiple insertions of aphIV and pat, and two l-phosphinothricin-selected lines plus three β-glucuronidase-positive lines recovered without selection. Although fertile plants were recovered from young proliferative cultures, transgenic plants, which were derived from cultures 12-14 months of age, were sterile.