Ovary-specific transcriptomes and the essential role of vitelline membrane protein 26Ab in embryonic desiccation resistance and female fertility of Zeugodacus tau.

Zeugodacus tau (Walker) is a globally significantly agricultural pest with severe economic and ecological impacts. Transcriptome sequencing-based data analysis has proven instrumental in identifying key functional genes in insects. However, the limited availability of transcriptome data has impeded the mining of functional genes in Z. tau. We conducted transcriptome sequencing on the midgut, Malpighian tubules, fat body, and ovary of 5-day old female Z. tau. Using a standard screening pipeline, we identified 2458 ovary-specific genes, which was much larger than that in other tissues. To verify the transcriptomic datasets, twelve randomly chosen ovary-specific genes were validated using quantitative real-time PCR (RT-qPCR), and their expression patterns were consistent with the RNA-seq data. Among these validated genes, we focused on a vitelline membrane protein (Vmp) gene, Vmp26Ab, which was involved in insect eggshell formation and maintaining the structural integrity of egg. Simultaneously, we identified two additional Vmp genes (Vmp26Aa and Vmp26Aa-like) by searching the transcriptome and genome of Z. tau. Amino acid sequences analysis revealed that all ZtVmps contained conserved proline-rich VM domains. RT-qPCR results showed that ZtVmps were highly expressed in the ovaries of 5-day-old and 9-day-old females Z. tau, and their expression levels were all upregulated under induction by 1 μg of 20-hydroxyecdysone (20E). RNA interference (RNAi) bioassay demonstrated that knockdown of Vmp26Ab facilitated embryonic water loss and reduced hatchability of eggs. These findings suggest that Vmp26Ab represents a potential target for developing RNA-based pesticides aimed at disrupting pest reproduction.