Selection and validation of reference genes for quantifying gene expression in the Gill's mealybug

Area of Science:

• Entomology
• Molecular Biology
• Pest Management

Background:

• The Gill's mealybug (Ferrisia gilli) is a significant pest impacting pistachio production in California.
• The recent description of F. gilli necessitates the validation of reference genes for accurate gene expression analysis using quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

Purpose of the Study:

• To select and validate commonly used reference genes for normalizing qRT-PCR data in Ferrisia gilli.
• To identify the most stable reference genes across different geographical populations and host plants.

Main Methods:

• Eight candidate reference genes (RPS8, TBP, UBQE2, RPL7, RPL5, RPL40, RPLP1, and HEL) were evaluated for expression stability.
• Gene stability was assessed in F. gilli populations from various pistachio orchards and fed on different host plants (pistachio, almond, grapes, lima beans).
• Stability analysis was performed using geNorm, NormFinder, BestKeeper, and RefFinder software.

Main Results:

• Three ribosomal protein genes (RPS8, RPL40, and RPL7) were identified as the most stable reference genes.
• These validated genes are suitable for normalizing qRT-PCR data in F. gilli under diverse experimental conditions.

Conclusions:

• The validated reference genes (RPS8, RPL40, RPL7) provide a reliable tool for gene expression studies in Ferrisia gilli.
• These findings will facilitate advancements in resistance monitoring, molecular toxicology, and functional genomics research for this major pistachio pest.