High Frequency Induction and Transformation of Somatic Embryos From Mature Seed-derived Leaf in Soybean

Objective Although many improvements in soybean transformation have been made, the efficiency of transformation is still low. Thus, a more useful and efficient soybean transformation system required to be established. The objective of this study is to develop high frequency induction and transformation of somatic embryos (SEs) using mature seed-derived leaf (MSDL) of soybean as target explants. Methods The leaves detached from 7-d-old germinated seedlings were divided into 1.2 cmx1.2 cm sections. These sections were used to induce somatic embryogenesis on the embryo induction medium (EIM) and to infect with Agrobacterium EHA105 strain harboring the pCAMBIA1301 for transformation. Results The MSDL including primary leaf and secondary leaf was able to produce SEs. Most of SEs occurred along the incision of leaves. This system was shown to be applicable to different genotypes. The highest induction frequency of SEs was 95.0% and the average transformation efficiency based on & beta;-glucuronidase (GUS) assay reached to 75.4%. The transgenic events were further confirmed by Southern blot. Conclusion High frequency induction and transformation of somatic embryos using soybean MSDL as target tissue were developed in this study. This system can be applied to the development of genome editing technology in soybean.