Expression Analysis of Genes Related to Rice Resistance Against Brown Planthopper, Nilaparvata lugens

Brown planthopper (BPH) is an insect species that feeds on the vascular system of rice plants. To examine the defence mechanism of rice plants against BPH, the pathogenesis-related genes (PR1a, PR2, PR3, PR4, PR6, PR9, PR10a, PR13, PR15 and PRpha), signaling molecule synthesis genes (AOS, AXR, ACO and LOX), antioxidant-related genes (CAT, TRX, GST and SOD) and lignin biosynthesis-related genes (CHS, CHI and C4H) were investigated in a resistant rice variety. AOS, PR6, PR9 and PR15 genes showed significantly increased relative expression levels at 24.38-, 19.17-, 14.71-, and 12.74-fold compared to the control. Moderate increased relative expression levels of lignin biosynthesis-related gene (C4H), pathogenesis-related genes (PR4, PR10a and PRpha), and antioxidant-related gene (GST) were found, while CHI, LOX, SOD, TRX1 and AXR showed decreased relative expression levels. It was thus clearly shown that wound-induced response genes were activated in rice plants after BPH attacks through AOS activation. Jasmonic acid signaling molecule may activate PR6, PR15, GST and CAT subsequently increasing their expression for H2O2 detoxification. PR6 were expressed at the highest relative level among the PR genes. These genes therefore have also a considerable synergistic role with the other genes against BPH by interfered their digestion tract system.