|HAVILAND, DAVID - University Of California - Cooperative Extension Service
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2023
Publication Date: 10/18/2023
Citation: Bansal, R., Haviland, D., Hunter, W.B. 2023. Selection and validation of reference genes for quantifying gene expression in the Mealybug, Ferrisia gilli Gullan (Hemiptera: Pseudococcidae). Journal of Economic Entomology Biological Control. https://doi.org/10.1093/jee/toad179.
Interpretive Summary: The gill’s mealybug (GMB) is one of the most important pests of pistachio in California. There are no validated reference genes to normalize the gene expression for real-time quantitative reverse transcription-PCR (qRT-PCR) in this insect. We selected and validated eight commonly used reference genes for their stability across geographical populations and insects fed with different host plants. Ribosomal genes were identified as the most stable across all treatments, and thus were recommended for normalizing the qRT-PCR data. These findings will support the accurate screening and monitoring the insecticide resistance in GMB. Further, results of this study lay the foundation for molecular toxicology and functional genomics research to investigate several basic and applied aspects of biology and management challenges in GMB.
Technical Abstract: The Gill’s mealybug, Ferrisia gilli Gullan, (Hemiptera: Pseudococcidae) has emerged as a major pest of pistachio in California. Because F. gilli is only relatively recently described, there are no validated reference genes to normalize the expression data from real-time quantitative reverse transcription–polymerase chain reaction (qRT-PCR) in this species. We selected and validated 8 commonly used reference genes (RPS8, TBP, UBQE2, RPL7, RPL5, RPL40, RPLP1, and HEL) for expression stability in F. gilli. These genes were evaluated in 5 different geographical populations of F. gilli collected from organic and conventionally grown pistachio orchards. Candidate reference genes were also evaluated in F. gilli fed with 4 plant hosts: pistachio, almond, grapes, and lima beans. The stability of candidate genes was analyzed using 4 software algorithms: geNorm, NormFinder, BestKeeper, and RefFinder. Three genes RPS8, RPL40, and RPL7 encoding for ribosomal proteins were identified as the most stable across the treatments and thus were recommended for normalizing the qRT-PCR data. These findings will support resistance monitoring, molecular toxicology, and functional genomics research in F. gilli.