Transcriptome analysis reveals differentially expressed genes between the ovary and testis of the honey bee Apis mellifera

Honey bees (Apis mellifera) are an important social pollinator, crucial in maintaining ecological balance and biodiversity. The haploid-diploid sex determination system determines their sexes where males are haploids formed from unfertilized eggs while females are diploids formed from fertilized eggs. To better understand the gonad differentiation mechanism in honey bees, here the transcriptome difference between the honey bee ovary and testis were analyzed using the Illumina sequencing technology. A total of 4380 differentially expressed genes (DEGs) were identified, with 2255 up-regulated and 2125 down-regulated in the ovary compared to the testis. Among these, many candidate DEGs related to sex determination, spermatogenesis, and oogenesis were identified, such as csd, fem, and dsx. Moreover, 3092 differentially expressed alternative splicing events (ASEs) related to 1497 genes, such as tra2, ovo, and squid, were identified between the ovary and testis. The findings of this study provide valuable information on gene expression for understanding the underlying molecular mechanisms of gonad differentiation and gametogenesis in A. mellifera.