Effect of Salicylic Acid on Pear Leaf Induced Resistance to Pear Ring Rot

To reveal the mechanism of resistance of pear against ring rot induced by SA, the influence of SA treatment on disease severity and plant defense enzymes were studied with Pyrus bretschneideri cv. Yali and Physalospora piricola Nose as the materials. It is interesting to note that the resistance of pear to P. piricola could be greatly increased by the treatment of 0.2 mM SA. In the present study, plant defense responses were induced in pear leaves using marker enzymes such as superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia-lyase (PAL), polyphenol oxidases (PPO), -1, 3-glucanase and chitinase. In the inoculated leaves, the SA-treatment enhanced the activities of POD, PAL, PPO, -1, 3-glucanase and chitinase. It was observed that the PR-proteins responded quickly to pathogen infection. These results clearly demonstrate that SA could induce the systemic acquired resistance and strengthen antiviral capability of pear to P. piricola.