Biological and molecular comparison between localized and systemic acquired resistance induced in tobacco by a Phytophthora megasperma glycoprotein elicitin.
We have compared localized (LAR) and systemic (SAR) acquired resistance induced in tobacco by a hypersensitive response (HR) inducing Phytophthora megasperma glycoprotein elicitin. Three different zones were taken into account: LAR, SAR(T) and SAR(S). The LAR zone was 5-10 mm wide and surrounded the HR lesion. SAR(T) was the tissue of the elicitor-treated leaf immediately beyond the LAR zone. The systemic leaf was called SAR(S). Glycoprotein-treated plants showed enhanced resistance to challenge infection by tobacco mosaic virus (TMV). Disease resistance was similar in SAR(T) and SAR(S), and higher in LAR. The expression pattern, in glycoprotein-treated plants, of acidic and basic PR1, PR2, PR3 and PR5 proteins and of O-methyltransferases (OMT), enzymes of the phenylpropanoid pathway, was similar to that in TMV-infected plants. OMT was stimulated in LAR but not in SAR(T) and SAR(S). The four classes of acidic and basic PR proteins accumulated strongly in LAR. Reduced amounts of acidic PR1, PR2, PR3 and only minute amounts of basic PR2 and PR3 accumulated in SAR(T) and SAR(S). In glycoprotein-treated plants, expression of the acidic and basic PR proteins in LAR and SAR of transgenic NahG and ETR tobacco plants and in LAR of plants treated with inhibitors of salicylic acid accumulation and of ethylene biosynthesis indicated a salicylic acid-dependent signalling pathway for acidic isoform activation and an ethylene-dependent signalling pathway for basic isoform activation.
Cordelier
Sylvain
S
Institut de Biologie Moléculaire des Plantes du C.N.R.S., Université Louis Pasteur. 12, rue du Général Zimmer, 67084 Strasbourg, France.
de Ruffray
Patrice
P
Fritig
Bernard
B
Kauffmann
Serge
S
D020418:Algal Proteins / Q000633:toxicity*; D006023:Glycoproteins / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics; D010838:Phytophthora / Q000472:pathogenicity*; D010935:Plant Diseases / Q000235:genetics; D018515:Plant Leaves / Q000821:virology; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011506:Proteins; D014026:Nicotiana / Q000235:genetics*; D014027:Tobacco Mosaic Virus / Q000472:pathogenicity
D020418:Algal Proteins; D006023:Glycoproteins; D010940:Plant Proteins; D011506:Proteins; C085101:elicitin, Phytophthora