An association between Dmnt1 and Wnt in the production of oocytes in the whitefly Bemisia tabaci

Authors: CUNNINGHAM, CHRISTOPHER - University Of Georgia; SHELBY, EMILY - University Of Georgia; MCKINNEY, ELIZABETH - University Of Georgia; Simmons, Alvin; MOORE, ALLEN - University Of Georgia; MOORE, PATRICIA - University Of Georgia

Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2024
Publication Date: 2/9/2024
Citation: Cunningham, C.B., Shelby, E.A., Mckinney, E.C., Simmons, A.M., Moore, A.J., Moore, P.J. 2024. An association between Dmnt1 and Wnt in the production of oocytes in the whitefly Bemisia tabaci. Insect Molecular Biology. https://doi.org/10.1111/imb.12893.
DOI: https://doi.org/10.1111/imb.12893

Interpretive Summary: Understanding the developmental process of insects is needed to develop ways to control them by disrupting their biology. We previously showed that Dnmt1 (DNA methyltransferase I) is important for forming both male and female reproductive cells in insects. In this study, we tested the hypothesis that Dmnt1 influences reproductive cell division in developing whiteflies. We generally did not find an overall effect on the genes affecting cell division in sperm or egg cells. However, we found that genes in a pathway called Wnt were differentially expressed when Dnmt1 expression was experimentally reduced, and we also characterized the biochemical process called methylation. The effect observed on Wnt presents an interesting new candidate pathway that will be useful to the scientific community in the development of molecular control strategies against whiteflies.

Technical Abstract: Producing viable gametes among metazoans relies on generally conserved genetic machinery. We have previously shown that DNA methyltransferase I (Dnmt1) plays an important role for both male and female gametogenesis in insects. In this study, we tested the hypothesis that Dmnt1 influences meiosis, a prediction from previous studies that suggested this is where gametogenesis is being perturbed. We used RNAi to reduce the gene expression of Dnmt1 within the whitefly Bemisia tabaci, one of the species that relies on Dnmt1 for proper gametogenesis. We then used RNA-seq to test an a priori hypothesis that meiosis related molecular pathways would be perturbed. This was done by comparing Dnmt1 RNAi and control samples. We generally did not find an overall effect on meiosis genes. However, we found that genes in the Wnt pathway, genes associated with the entry into meiosis in vertebrates, were differentially expressed when Dnmt1 expression was experimentally reduced. Our results are consistent with Dnmt1 knockdown influencing specific pathways and not causing general transcriptional response. This is a finding that is also seen with other insect species. We also characterized the methylome of B. tabaci and assessed the influence of Dnmt1 knockdown on cytosine methylation. This species has methylome characteristics comparable to other Hemipterans; overall level, enrichment within gene bodies, and bimodal distribution of methylated/non-methylated genes. Very little differential methylation was observed and difference of methylation were not associated with differences of gene expression. The effect on Wnt presents an interesting new candidate pathway for future studies.