Transcriptional Profiles of Diploid Mutant <i>Apis mellifera</i> Embryos after Knockout of <i>csd</i> by CRISPR/Cas9

• Main Authors: Xiuxiu Wang, Yan Lin, Liqiang Liang, Haiyang Geng, Meng Zhang, Hongyi Nie, Songkun Su
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Insects
• Subjects: <i>Apis mellifera</i>; sex determination; CRISPR/cas9; transcriptome
• Online Access: https://www.mdpi.com/2075-4450/12/8/704

In honey bees, <i>complementary sex determiner</i> (<i>csd</i>) is the primary signal of sex determination. Its allelic composition is heterozygous in females, and hemizygous or homozygous in males. To explore the transcriptome differences after sex differentiation between males and females, with genetic differences excluded, <i>csd</i> in fertilized embryos was knocked out by CRISPR/Cas9. The diploid mutant males at 24 h, 48 h, 72 h, and 96 h after egg laying (AEL) and the mock-treated females derived from the same fertilized queen were investigated through RNA-seq. Mutations were detected in the target sequence in diploid mutants. The diploid mutant drones had typical male morphological characteristics and gonads. Transcriptome analysis showed that several female-biased genes, such as <i>worker-enriched antennal</i> (<i>Wat</i>), <i>vitellogenin</i> (<i>Vg</i>), and some venom-related genes, were down-regulated in the diploid mutant males. In contrast, some male-biased genes, such as <i>takeout</i> and <i>apolipophorin-III-like protein</i> (<i>A4</i>), had higher expressions in the diploid mutant males. Weighted gene co-expression network analysis (WGCNA) indicated that there might be interactions between <i>csd</i> and <i>fruitless</i> (<i>fru</i>), <i>feminizer</i> (<i>fem</i>) and <i>hexamerin 70c</i> (<i>hex70c</i>), <i>transformer-2</i> (<i>tra2</i>) and <i>troponin T</i> (<i>TpnT</i>). The information provided by this study will benefit further research on the sex dimorphism and development of honey bees and other insects in Hymenoptera.