Agrobacteriuni-mediated transformation of a Dendrobium orchid with the class 1 knox gene DOH1

Transgenic orchid (Dendrobium Madame Thong-In) plants were regenerated by i noculating thin-section explants from protocorm-like bodies (PLBs) with Agr obacterium tumefaciens strain LBA4404 harboring a binary vector that carrie d the orchid DOH1 antisense gene. The transformation was performed through two consecutive stages of cocultivation, with the first stage occurring on antibiotic-free medium for 3 days and the subsequent stage on medium contai ning 50 mg/l carbenicillin for 3-4 weeks. Proliferated PLBs were repeatedly selected for kanamycin resistance. The presence and expression of the tran sgene were assessed by molecular analyses. Expression of the DOH1 antisense gene caused abnormal multiple shoot development, indicating a role for DOH 1 in the basic plant architecture in orchid.