This study aims to investigate the role of highly expressed genes (HEGs) in the midguts of Apis cerana cerana workers responding to Nocema ceranae stress, normal 7- and 10-old day workers’ midguts (Ac7CK and Ac10CK) and N. ceranae-stressed 7- and 10-old day workers’ midguts (Ac7T and Ac10T) were analyzed using RNA-seq, bioinformatics and RT-PCR. 1809736786 raw reads were produced, and 1562162742 clean reads with Q30 ≥93.34% were gained after quality control; Pearson correlations between every sample within each group were above 0.8728. Based on the standard of FPKM value >15. 3163, 3312, 3305 and 2426 HEGs were screened out from Ac7CK, Ac7T, Ac10CK and Ac10T, respectively. Venn analysis showed there were 2074 shared HEGs in aforementioned four groups, and the number of specific HEGs were 89、283、156 and 78, respectively. GO classifications indicated specific HEGs in Ac7T and Ac10T were repsectively associated with 35 and 28 GO terms, among them cellular process was the largest one. Moreover, KEGG pathway enrichment analysis demonstrated specific HEGs in Ac7T and Ac10T were repsectively enriched in 39 and 37 pathways, and ribosome and protein processing in endoplasmic reticulum were the mostly abundant. Further exploration showed host material and energy metabolisms as well as cellular and humoral immune were activated to various degrees; additionally, close interactions existed between A. cerana cerana and N. ceranae. Finally, eight shared HEGs were randomly selected for RT-PCR validation, and signal bands were sucessfully amplified from them, indicative of the authenticity of HEGs in the study. These findings not only reveal the expression profile and putative role of host HEGs during the responses of A. cerana. cerana to N. ceranae stress, but also offer beneficial and valuable information for uncovering the molecular mechanisms regulating of host stress responses and A. cerana cerana-N. ceranae interactions.
