title: Transgene expression in strawberries driven by a heterologous phloem-specific promoter.
abstract: Strawberry is susceptible to diseases caused by phytoplasmas, mycoplasma-like prokaryotes restricted to sieve elements in the phloem tissue of infected plants. One strategy to improve strawberry resistance to phytoplasmas involves transgenic expression of anti-microbial peptide genes in phloem. For targeted phloem-specific expression, we constructed a binary vector with an expression cassette bearing the beta-glucuronidase (GUS) reporter gene (uidA) under control of the Arabidopsis sucrose-H+ symporter gene (AtSUC2) promoter. Transgenic strawberry lines were generated with high efficiencies by a modified transformation protocol, which combines the adoption of a 3-day pre-selection period following transformation, and the addition of 10-microM thidiazuron to the regeneration medium. Histological GUS activity indicated that the reporter gene was expressed specifically in phloem of leaves, petioles, and roots of transgenic plants. The results suggest that the transformation protocol and the AtSUC2 promoter may be useful for engineering phytoplasma-resistant transgenic strawberries.
authors.affiliation: Molecular Plant Pathology Laboratory, USDA-Agriculture Research Service, Beltsville, MD 20705, USA. zhaoy@ba.ars.usda.gov
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Liu
authors.forename: Robert E
authors.initials: RE
authors.lastname: Davis
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D031985:Fragaria / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017930:Genes, Reporter / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics; D005966:Glucuronidase / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics; D010671:Phenylurea Compounds / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D013830:Thiadiazoles / Q000494:pharmacology; D014162:Transfection / Q000379:methods; D014170:Transformation, Genetic / Q000235:genetics*; D019076:Transgenes / Q000235:genetics*
chemical_list: D026901:Membrane Transport Proteins; D010671:Phenylurea Compounds; D010940:Plant Proteins; D013830:Thiadiazoles; C078729:sucrose transport protein, plant; C016785:thidiazuron; D005966:Glucuronidase