Functional study of transcription factor NlMyc in regulating the virulence of brown planthopper (Nilaparvata lugens) to tritin-enhanced resistance rice

NlMyc is an extremely important transcription factor in living organisms, playing a crucial role in a various of cellular activities, including cell cycle, growth, proliferation, and apoptosis among others. However, how transcription factors regulate the virulence of brown planthopper (Nilaparvata lugens (Stål)) on rice remains unreported. This study cloned and identified the transcription factor NlMyc gene of brown planthopper, revealing a full-length sequence of 1 830 bp encoding 609 amino acids. Using RT-qPCR technology to detect the resistance expression level of NlMyc gene and its spatio-temporal expression pattern in brown planthopper, the study found that the expression level of NlMyc gene was significantly higher after brown planthopper fed on resistant rice than that of brown planthopper fed on susceptible rice, and the expression level of NlMyc gene was the highest in 1-day-old female adults and salivary gland tissues. After RNAi silencing of NlMyc gene, the number of feeding holes of brown planthopper on tricin-enhanced resistant rice significantly increased to (28.9 ± 8.5), compared to the control groups (Control, dsGFP), which were (13.5 ± 4.3) and (16.2 ± 8.4) feeding holes, respectively. Additionally, the average honeydew secretion of brown planthopper treated with dsNlMyc, Control and dsGFP for 48 hours was 2.44 mg, 5.30 mg and 4.60 mg, respectively; the weight gain was 0.23 mg, 0.49 mg, and 0.47 mg, indicating a significant decrease in honeydew secretion and weight gain in the dsNlMyc group compared to the control groups. This indicated that silencing the NlMyc gene impaired the fitness and feeding ability of brown planthopper, thereby regulated the virulence of brown planthopper on resistane rice. This study demonstrates that NlMyc is a key transcription factor regulating the virulence of brown planthopper on tricin-enhanced resistant rice, which not only provides new insights into the exploration of the virulence variation of brown planthopper, but also offers a novel molecular target for pest control.