Abstract: 【Aim】 The brown planthopper, Nilaparvata lugens, is one of the most destructive pests of rice. This study aims to investigate the relationship between acetylcholinesterase (AChE) and the apoptosis in midgut cells of N. lugens induced by host rice resistance. 【Methods】 Primary cells were isolated from the midgut of the 4th instar nymph (biotype Ⅰ) of N. lugens. The first-generation subculture cells were treated with juice from rice seedlings with different resistance levels. Subcellular localization and expression of AChE were detected by using cell immunohistochemistry and real-time fluorescence quantitative PCR techniques, respectively. 【Results】 No green fluorescent signals representing apoptotic nuclei were detected in the untreated control cells, but these cells exhibited few signals in immunohistochemistry reaction, suggesting a basal expression level of AChE within the cells. The cells treated with the juice from seedlings of the susceptible rice variety TN1 and two resistant rice varieties B5 and TKM-6 displayed apoptosis with the apoptotic rate of 8%, 65% and 85%, respectively. Immunohistochemistry reaction revealed that all apoptotic cells showed stronger signals representing overexpression and accumulation of AChE in the cytoplasm. AChE assembled around the nuclei instead of shifting to apoptotic bodies in the late apoptotic stage. The data from real-time fluorescence quantitative PCR showed 29.9-, 18.4- and 8-fold over-expression of AChE in cells treated with the juice from seedlings of TKM-6, B5 and TN1, compared with that in the control cells, which was consistent with the results from the immunohistochemistry detection. 【Conclusion】 The results confirm that host rice resistance is positively correlated with apoptosis in midgut cells of N. lugens, and AChE is overexpressed in apoptotic cells. These findings provide some valuable information for understanding the interaction mechanism of N. lugens and host rice, promoting breeding of novel resistant rice varieties and developing effective control strategies.

Key words: Nilaparvata lugens; acetylcholinesterase (AChE), midgut apoptosis, cell immunohistochemistry, real-time fluorescence quantitative PCR