Regulatory networks of mRNAs and miRNAs involved in the immune response of diamondback moth, Plutella xylostella to fungal infection.

Background: The entomopathogenic fungus, Isaria fumosorosea, shows promise as a biological control agent in managing the diamondback moth (DBM) Plutella xylostella, a highly destructive global pest of cruciferous vegetables. To date, the miRNA-mRNA regulatory networks underlying the immune response of DBM to I. fumosorosea infection are still poorly understood. Here, we characterize the expression profiles of miRNA and mRNA, and construct the miRNA-gene regulatory network in DBM infected with I. fumosorosea.

Results: We identified 580 differentially expressed genes (DEGs) and 55 differentially expressed miRNAs (DEMs) in I. fumosorosea-infected DBM. Among these DEGs, we found 28 immunity-related genes, which mainly include pattern recognition receptors, signal modulators, and immune effectors. Integrated analysis discovered 87 negative correlation pairs between miRNA and mRNA, involving 40 DEMs and 62 DEGs in infected DBM. Additionally, 13 miRNAs and 10 corresponding mRNAs were identified as candidate miRNA-mRNA pairs for DBM immunity against fungal infection. Gene functional enrichment analysis indicated that these miRNAs could target genes associated with various pathways, such as the immune system, infectious diseases, digestive system, endocrine system, nervous system, and signal transduction. Finally, the regulatory relationships of six miRNA-mRNA pairs were validated using quantitative reverse transcription PCR.

Conclusions: For the first time, we present integrated miRNA and mRNA data to elucidate the immune response of the DBM to fungal infection. Our findings enhance the understanding of the immune response of the DBM to entomopathogenic fungi infection.