Genetics, anatomy and expression of antisense ACC oxidase gene in transgenic Dendrobium draconis Rchb.f.

This research was aimed to compare chromosome number, anatomy and expression ofantisense ACC oxidase gene between nontransgenic and transgenic Dendrobium draconis Rchb.f.obtained by Homkrajae (2005). Plant materials were cultivated on modified MS medium supplementedwith 5 mg/L hygromycin and 15% coconut water for four months. It was found that the frequency ofhygromycin-resistant D. draconis was 80 % while 20 % were escape plants. One hundred percent of thehygromycin-resistant plants were viable when further cultured on the same medium for eight months.GUS assay used to verify transient gene expression in transgenic D. draconis showed positive results. Ananatomical study in leaves, stems and roots of transgenic plants showed positive blue coloration in alltissues while those of nontransgenic plants showed negative results. PCR analysis confirmed theintegration of 35S promoter, NOS terminator and antisense ACC oxidase gene in D. draconis. Acytological study revealed that there was no change in chromosome number (2n=38). Furthermore, bothtransgenic and nontransgenic orchids exhibited no significant difference in chlorophyll content