Agrobacterium-mediated transformation of the wild orchid species Phalaenopsis amabilis

Phalaenopsis hybrids constitute a major ornamental crop. An important parent species for many of these hybrids is Phalaenopsis amabilis. We developed a convenient method for the genetic modification of P. amabilis using Agrobacterium tumefaciens. The transformed intact protocorms, which are young orchid seedlings of P. amabilis, regenerated plants under the same conditions that showed the highest frequency of shooting. A kanamycin resistance gene under the control of the 35S promoter can be used as a selective marker. In addition, T-DNA vectors containing the Arabidopsis class 1 KNOX gene, BP/KNAT1, were successfully introduced into protocorms. Shoots were generated with an abnormal leaf shape that was easily distinguished from that of normal shoots, indicating that BP/KNAT1 can be used as a visible marker gene. Furthermore, the protocorms transformed with BP/KNAT1 produced multiple shoots. Both the presence and expression of the transgene in transformed plants were confirmed by molecular analysis.