2.2 Differentially expressed genes (DEG) analysis
mRNA-seq method was the same as description in our previous article (Zhanget al. 2019), including RNA extraction, six cDNA libraries construction, illumina Hiseq 4000 sequencing, de novo assembly, unigene annotation and functional classification (Patro et al.2017). The expression level for unigenes were calculated by TPM using Salmon (Mortazavi et al. 2008). DEG were selected with P < 0.05 and fold change > 2 using R package edgeR (Robinson et al. 2010). KEGG pathway enrichment analysis of DEG was the same as description in our previous article, and so as DEP and DEM (Zhang et al. 2019).