Different expression pattern of NPR1 and some of the pathogenesisrelated genes in response to salicylic acid and methyl jasmonate treatment in rice

Salicylic acid (SA) and Jasmonic acid (JA) signaling pathways are mutually antagonistic and sometimes synergistic. This regulatory cross talk may have evolved to allow plants to fine-tune the induction of their defenses in response to different plant pathogens. NPR1 plays a significant role in regulating the interaction of salicylic acid and methyl jasmonate pathway. In fact, NPR1 activation depends on the levels of these two hormones in plant. Therefore, antagonistic and synergistic effects of salicylic acid and methyl jasmonate spraying were investigated on the expression of the genes NPR1, Thionin, PDF1.2 and PR1 using Real time PCR technique in two rice cultivars Khazar (resistant to blast) and Hashemi (susceptible to blast) at 0, 6, 12, 24 and 48h after spraying. Results showed that the studied genes had different expression patterns in different genotypes and times after spraying, in response to salicylic acid and methyl jasmonate, indicating an association between regulatory pathways of these hormones and induction of the defense related genes. The expression of the studied genes was increased by SA and MJ treatment in khazar, while no significant differences were observed among different times after SA and MJ treatment for PR1 in Hashemi. The expression of the other genes was also low in this cultivar. In general, it could be concluded that antagonistic and synergistic effects of SA and MJ lead to changes in the expression of the genes studied at different times after spraying and in the formation of the immune system in resistance genotype.