Gene direction and functions were annotated based on the Nr annotations. Gene ontology (GO) annotations with the default parameters were analyzed by the Blast2GO program, which were clustered into three groups including biological process, cellular component, and molecular function. Furthermore, the identification of differentially expressed genes (DEGs) between the NI and I libraries was conducted using a rigorous algorithm at false discovery rate (FDR)-adjusted p-value < 0.05. GO term2 was assigned to DEGs based on the above GO annotations. In addition, GO enrichment analysis was performed to search significantly enriched functional classification.