Abstract: 【Aim】 To explore how the brown planthopper (Nilaparvata lugens) adapts to the resistant rice variety YHY15 and lay a foundation for studying the role of circular RNA (circRNA) in the adaptation mechanism of N. lugens to resistant rice. 【Methods】 The circRNAs of biotype 1 and biotype Y (biotype that can cause damage to resistant rice YHY15) of N. lugens were identified by high-throughput sequencing technology, and the type and distribution of circRNAs were counted. The expression differences of circRNAs between biotype 1 and biotype Y of N. lugens were analyzed, and GO functional annotation and KEGG enrichment analysis of the circRNA source genes were performed. 【Results】 A total of 19 circRNAs were identified in biotype 1 and biotype Y of N. lugens, and distributed on nine chromosomes. Among them, 17 circRNAs were composed of exons between splicing sites, two circRNAs were composed of all bases between splicing sites, and 17 circRNAs were 200-800 bp in length. The expression abundance and expression level of circRNAs in biotype Y of N. lugens were higher than those in biotype 1 of N. lugens. The analysis results showed that in the process of biotype 1 of N. lugens overcoming the resistance of rice YHY15 to form a new biotype Y of N. lugens, under the pressure of natural selection, the expression of circRNA changed resulting in the effects on the formation of a new biotype of N. lugens. The KEGG analysis results indicated that the identified circRNA source genes of biotype 1 and biotype Y of N. lugens were mainly enriched in autophagy-related pathways. 【Conclusion】 Long-term feeding of resistant rice by N. lugens leads to the evolution of the digestion, detoxification, and metabolic abilities of N. lugens, which can degrade the secondary metabolites produced by resistant rice to resist N. lugens. The circRNA source genes of biotype 1 and biotype Y of N. lugens are enriched in autophagy-related pathways, indicating that N. lugens respond to insect-resistant rice through the process of autophagy. This response promotes the adaptation of N. lugens to insect-resistant rice, enhances pathogenicity, and forms biotypes.

Key words: Nilaparvata lugens; circRNA, autophagy, insect-resistant rice, high-throughput sequencing