The unigenes were annotated with the National Center for Biotechnology Information non-redundant databases (NR), Gene Ontology (GO), Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases using BLASTX searches (E-value ≤ 1.0e−5). The Blast2GO software package and WEGO software were employed to compare and determine unigenes’ GO annotations and obtain GO functional classifications for all annotated unigenes (Götz et al. 2008; Ye et al. 2006).