The assembly of Y chromosome reveals amplification of genes regulating male fertility inBactrocera dorsalis

Abstract

AbstractBACKGROUNDThe oriental fruit flyBactrocera dorsalisis an invasive pest causing considerable ecological and economic damage worldwide. The Y chromosome is an important target for the sterile insect technique (SIT) but its sequence and structure has been poorly explored.RESULTSWe assembled the genome ofB. dorsalisat the chromosome level with a total size of 562.6 Mb. The assembly includes a ∼7.6 Mb Y chromosome sequence, being the first reported Y chromosome in Tephritidae. The assembled Y chromosome is highly repetitive, and contains 61 genes, including 9 multi-copy genes. We surprisingly found that the M factor (MoY) in Tephritidae has multiple copies, verified by our droplet digital PCR (ddPCR) analysis. Besides, we identified 32 copies ofgyf-like on the Y chromosome(gyfY) that were highly expressed in testis. RNAi targeting thegyfYresulted in depletion of live sperms, suggesting that the amplification ofgyfYis essential for male fertility, which facilitated the understanding of high fecundity of this invasive insect.CONCLUSIONWe reported firstly the Y chromosome ofBactrocera dorsalis. Our results will also provide target genes for CRISPR/Cas9 based SIT, leading to the development of novel control strategies against tephritid flies.