Introduction of pathogen defense genes and a cytokinin biosynthesis gene into sugarbeet (Beta vulgaris L.) by Agrobacterium or particle bombardment

Two different methods for sugarbeet (Bera vulgaris L.) transformation were developed, one using Agrobacterium with excised cotyledons, the other, particle bombardment of embryogenic hypocotyl callus. Transformation efficiencies averaged 0.7% for the Agrobacterium method (number of transgenic plants obtained per treated cotyledon) and about 8% for the bombardment method (number of transgenic plants obtained per plate of embryogenic callus treated). Transgenic sugarbeet plants were produced carrying genes encoding either pathogen-defense-related proteins or the reporter enzyme beta-glucuronidase (GUS) under transcriptional control of stress- or wound-inducible promoters. In addition, two plants were regenerated carrying a gene associated with enhanced insect resistance, the cytokinin biosynthesis gene, fused to a patatin gene promoter from potato. Expression of the GUS gene (gusA) under the control of the tobacco osmotin promoter was wound inducible with detectable activity at 8 h and maximal activity at 72 h post-wounding.