Validation of reference genes for quantitative expression analysis by real-time rt-PCR in four lepidopteran insects

Area of Science:

• Molecular Biology
• Genetics
• Entomology

Background:

• Quantitative real-time polymerase chain reaction (qPCR) is vital for gene expression studies.
• Housekeeping genes (HKGs) are commonly used as reference genes for normalization in qPCR.
• The stability of HKGs across different species and conditions is often not rigorously validated.

Purpose of the Study:

• To evaluate the expression stability of six candidate HKGs in four lepidopteran insect species.
• To determine the most suitable reference genes for qPCR data normalization in Bombyx mori, Plutella xylostella, Chilo suppressalis, and Spodoptera exigua.
• To highlight the importance of validating HKG expression stability for reliable qPCR results.

Main Methods:

• Selection of six HKGs: actin A3, actin A1, GAPDH, G3PDH, E2F, and rp49.
• Assessment of HKG expression stability across different developmental stages and tissues in four lepidopteran species.
• Utilized geNorm, NormFinder, stability index, and ΔCt analysis algorithms for evaluation.

Main Results:

• Actin A1 was most stable in P. xylostella and C. suppressalis, but least stable in B. mori and S. exigua.
• Rp49 and GAPDH showed the highest stability in B. mori and S. exigua, respectively.
• GAPDH, E2F, and Rp49 were the most stable in different tissues of B. mori, S. exigua, and C. suppressalis, respectively.

Conclusions:

• No single housekeeping gene is universally suitable as a reference gene for qPCR across all four lepidopteran species studied.
• Expression stability of HKGs varies significantly among closely related species and even within different tissues of the same species.
• Validation of HKG expression stability is indispensable before their use as internal controls in qPCR experiments to ensure accurate gene expression data.