Selection of Phalaenopsis amabilis L. Blume Orchid Resistance to Hygromycin

Examination of Phalaenopsis amabilis orchid resistance to hygromycin antibiotic is an important step to doprior to Agrobacterium-mediated genetic transformation in this orchids using Hygromycin phosphotransferase(HPT) gene as a selection marker in the T-DNA that harboring a desired gene to be transfered. We exposedthe plant on hygromycin containing medium. The experiment was conducted using 6 weeks old P. amabilisprotocorms. These protocorms were subcultured onto NP medium supplemented with various concentrationof Hygromycin (0, 5, 10, 20, 1nd 40 mg/l). The number of survival protocorms were examined every week for4 weeks after subcultured (WAS). The resistancy of hygromycin was calculated as ratio of death protocormsper total protocorms). The result showed that 10 mg/l hygromycin with 1 weeks of application caused deathclose to LD 50. This data indicate that P. amabilis resistance to hygromycin treatment on the appropriateconcentration 10 mg/l, and this concentration can be used for other purposes in orchid system.

Expression of Hygromycin Phosphotransferase Alters Virulence of Histoplasma capsulatum

ABSTRACT The Escherichia coli hygromycin phosphotransferase (hph) gene, which confers hygromycin resistance, is commonly used as a dominant selectable marker in genetically modified bacteria, fungi, plants, insects, and mammalian cells. Expression of the hph gene has rarely been reported to induce effects other than those expected. Hygromycin B is the most common dominant selectable marker used in the molecular manipulation of Histoplasma capsulatum in the generation of knockout strains of H. capsulatum or as a marker in mutant strains. hph-expressing organisms appear to have no defect in long-term in vitro growth and survival and have been successfully used to exploit host-parasite interaction in short-term cell culture systems and animal experiments. We introduced the hph gene as a selectable marker together with the gene encoding green fluorescent protein into wild-type strains of H. capsulatum. Infection of mice with hph-expressing H. capsulatum yeast cells at sublethal doses resulted in lethality. The lethality was not attributable to the site of integration of the hph construct into the genomes or to the method of integration and was not H. capsulatum strain related. Death of mice was not caused by altered cytokine profiles or an overwhelming fungal burden. The lethality was dependent on the kinase activity of hygromycin phosphotransferase. These results should raise awareness of the potential detrimental effects of the hph gene.