Nitric Oxide and Hydrogen Peroxide Signaling in Brassica napus Resistance to Sclerotinia sclerotiorum Induced

Oligochitosan was applied by spraying it on Brassica napus leaves for control of Sclerotinia sclerotiorum(SS). The best inducing resistance concentration of oligochitosan was 50μg mL-1 and the best pretreated time was 3 days before inoculation with SS. The production of H2O2 and NO in epidermal cells induced by oligochitosan was investigated by epidermal strip bioassay and LSCM, using cell permeable fluorophore diaminofluorescein diacetate (DAF-2D) and 2’,7’- dichlorofluorescin diacetate (H2DCF-DA), respectively. Epidermal Brassica napus cells treated with oligochitosan resulted in a strong increase of intracellular NO and H2O2. Oligochitosan and NO donor sodium nitroprusside (SNP) induced the defense reaction against SS, and increased lipoxygenase (LOX) activity. mRNA levels of PDF1.2 were also induced by oligochitosan and SNP. Co-treatment of Brassica napus with oligochitosan and NO scavenger CPTIO blocked the inducing resistance. These results indicated that the defense response induced by oligochitosan was connected with NO pathway