Generation of fertile transplastomic soybean.

We describe here the development of a plastid transformation method for soybean, a leguminous plant of major agronomic interest. Chloroplasts from embryogenic tissue of Glycine max have been successfully transformed by bombardment. The transforming DNA carries a spectinomycin resistance gene (aadA) under the control of tobacco plastid regulatory expression elements, flanked by two adjacent soybean plastome sequences allowing its targeted insertion between the trnV gene and the rps12/7 operon. All generated spectinomycin resistant plants were transplastomic and no remaining wild type plastome copies were detected. No spontaneous mutants were obtained. The transformation efficiency is similar to that of tobacco plastids. All transplastomic T0 plants were fertile and T1 progeny was uniformly spectinomycin resistant, showing the stability of the plastid transgene. This is the first report on the generation of fertile transplastomic soybean.