Objective To analyze the expression profile of the β-glucan-binding protein (Acβ-GBP) gene of Apis cerana cerana in response to Ascosphaera apis infection and to investigate the impacts of Acβ-GBP knockdown on the larval mortality and the incidence of chalkbrood disease following A. apis infection. These findings will provide a foundation for further functional research. Methods The sequence and structural characteristics of Acβ-GBP were analyzed via bioinformatics approaches. RT-qPCR was employed to investigate the expression profiles of Acβ-GBP in the larval midgut following A. apis infection. Furthermore, RNA interference (RNAi) was utilized to explore the impacts of Acβ-GBP on the larval mortality and the incidence of chalkbrood disease. Results The CDS length of Acβ-GBP was 1 440 bp, encoding a protein with a molecular weight of 54.68 kDa and a grand average of hydropathicity value of -0.22, which contained a typical transmembrane domain and signal peptide. Phylogenetic analysis revealed that β-GBP of A. c. cerana, Apis florea and Apis dorsata clustered into a single major clade. After A. apis infection, the expression level of Acβ-GBP in the midgut of A. c. cerana worker larvae was downregulated at 1-3 days post-infection (dpi) (P<0.05). Following RNA interference (RNAi)-mediated silencing of Acβ-GBP, its expression level was lower than that in the ds-egfp group at 2 and 3 dpi (P<0.01). The cumulative larval mortality and the incidence of chalkbrood disease both increased over the infection time, and the overall mortality was higher than that of the control group (P<0.000 1). Conclusion Acβ-GBP was capable of responding to A. apis infection, and knockdown of Acβ-GBP expression significantly impaired the resistance of honeybee larvae to A. apis. Collectively, β-GBP acts as an important immune recognition protein in A. c. cerana, and plays an important role in defending against fungal invasion.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |