Effect of the BTH Chemical Elicitor on Expression of the PR2 Gene and Fire blight Disease Severity in Quince

Application of elicitors for inducing plant defense genes is one of the methods used for controlling diseases. This research was carried out for evaluation of effects of the BTH elicitor on the PR2 gene expression and fire blight severity in quince. Two year- old quince plants of Isfahan and Torsh cultivars were treated with BTH at 400 mgl-1 twice at a four day interval. The treated trees were then infected with bacterium suspension and the disease severity was assessed after four weeks. Leaf samples were taken before inoculation and after extraction of RNA and synthesis of cDNA، a part of the PR2 gene was amplified with the degenerate primers and it was sequenced. Alignment of the sequence with other sequences in the data base showed high similarity with glucanases from other plants including apple. Specific primers were designed according to the sequence and expression of the PR2 gene was evaluated by real time PCR. The results showed that expression of the PR2 gene was increased several times after treatment of plants with BTH. Evaluation of the disease severity also showed % 21. 66 and %13. 76 decrease in plants treated with 400 and 300 mgl-1 BTH، respectively. These results show that decreasing the fire blight severity after treatment with the BTH elicitor could be related to induction of genes encoding PR proteins including PR2 and this material can be used in the integrated fire blight disease management program.