Overproduction of salicylic acid in plants by bacterial transgenes enhances pathogen resistance.
After a hypersensitive response to invading pathogens, plants show elevated accumulation of salicylic acid (SA), induced expression of plant defense genes, and systemic acquired resistance (SAR) to further infection by a broad range of pathogens. There is compelling evidence that SA plays a crucial role in triggering SAR. We have transformed tobacco with two bacterial genes coding for enzymes that convert chorismate into SA by a two-step process. When the two enzymes were targeted to the chloroplasts, the transgenic (CSA, constitutive SA biosynthesis) plants showed a 500- to 1,000-fold increased accumulation of SA and SA glucoside compared to control plants. Defense genes, particularly those encoding acidic pathogenesis-related (PR) proteins, were constitutively expressed in CSA plants. This expression did not affect the plant phenotype, but the CSA plants showed a resistance to viral and fungal infection resembling SAR in nontransgenic plants.
Verberne
M C
MC
Leiden/Amsterdam Center for Drug Research, Leiden University, Gorlaeus Laboratories, PO Box 9502, 2300 RA Leiden, The Netherlands.
Verpoorte
R
R
Bol
J F
JF
Mercado-Blanco
J
J
Linthorst
H J
HJ
D015152:Blotting, Northern; D005798:Genes, Bacterial; D007113:Immunity, Innate / Q000235:genetics; D008957:Models, Genetic; D010641:Phenotype; D010944:Plants / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism*; D010947:Plants, Toxic; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics; D014027:Tobacco Mosaic Virus / Q000472:pathogenicity; D014170:Transformation, Genetic; D015003:Yeasts / Q000472:pathogenicity
D020156:Salicylic Acid