Abstract: 【Aim】 This study aims to identify the IκB kinase (IKK) related genes in the small brown planthopper, Laodelphax striatellus, and to investigate its antiviral role in this insect, so as to further understand the innate immune mechanisms in insect vectors responsive to plant viruses. 【Methods】 The IKK related genes in the L. striatellus genome were identified and characterized using bioinformatics approach. The healthy and the rice stripe virus (RSV) infected planthopper were used as the materials. The expression levels of IKK related genes in various developmental stages (egg, 1-5 instar nymphs, male and female adults) and adult tissues (gut, salivary gland, hemolymph, fat body, ovary and testis) of the RSV-free planthoppers were detected by RT-PCR. The relative expression levels of IKK related genes in the above different developmental stages and adult tissues between the RSV-free and RSV-infected planthoppers were assayed by qRT-PCR. In addition, the transcription levels of coat protein (CP) gene indicating the accumulation levels of RSV were determined after RNAi by injection of the double-stranded RNA of IKK related genes in the 3rd instar nymph of RSV-infected planthoppers. 【Results】 Two IKK related genes, IKKα (GenBank accession number: MK903504) and TANK-binding kinase 1 gene TBK1 (GenBank accession number: MN124506), were identified in the genome of L. striatellus. The open reading frame (ORF) of IKKα is 2 379 bp in length, encoding 792 amino acids, while the ORF of TBK1 is 1 551 bp in length, encoding 516 amino acids. The proteins coded by both genes have a conserved serine/threonine kinase domain and a ubiquitin folding domain. The RT-PCR results confirmed that IKKα and TBK1 were ubiquitously expressed in various developmental stages and different adult tissues of RSV-free L. striatellus. Significant expression differences of IKKα and TBK1 in various developmental stages and different adult tissues between the RSV-free and RSV-infected planthoppers were observed. The accumulation level of RSV was significantly increased after RNAi of IKKα and TBK1 in the 3rd instar nymphs of the RSV-infected planthoppers, respectively. 【Conclusion】 The results indicate that IKKα and TBK1, the important genes of NF-κB signaling pathway, are widely expressed in L. striatellus and may play important roles in L. striatellus in response to RSV invasion. These results will contribute to the further investigation on antiviral immune pathway in insect vectors against plant virus.

Key words: Laodelphax striatellus, IKK, Rice stripe virus, NF-κB signaling pathway, qRT-PCR