Preparation of rice protoplasts,
transformation by electroporation, selection of transformed
calli, and regeneration of transgenic plants have all been
described (12, 18). The plasmid pLAN150 was digested at the
HindIII site, which is located immediately upstream of the
cauliflower mosaic virus (CaMV) 35S promoter, resulting in
a linear vector. The linearized plasmid was cotransformed
into rice protoplasts by electroporation with the hygromycinresistance
plasmid. Transformants were selected in a medium
containing hygromycin B (30 ,ug/ml), and plants were regenerated
from hygromycin-resistant calli