The gene for Vitreoscilla hemoglobin (VHb) has been introduced and expressed in Nicotiana tabaccum (tobacco). Transgenic tobacco plants expressing VHb exhibited enhanced growth, on average 80100% more dry weight after 35 days of growth compaired to wild-type controls. Furthermore, germination time is reduced from 68 days for wild-type tobacco to 34 days and the growth phase from germination to flowering was 35 days shorter for the VHb-expressing transgenes. Transgenic plants contained, on average, 3040% more chlorophyll and 34% more nicotine than controls. VHb expression also resulted in an altered distribution of secondary metabolites: In the transgenic tobacco plants anabasine content was decreased 80% relative to control plants.